Systems and methods for processing and transmitting sensor data

ABSTRACT

Systems and methods for processing, transmitting and displaying data received from an analyte sensor, such as a glucose sensor, are disclosed. In an embodiment, a method for transmitting data between a first communication device associated with an analyte sensor and a second communication device configured to provide user access to sensor-related information comprises: activating a transceiver of a first communication device associated with an analyte sensor at a first time; and establishing a two-way communication channel with the second communication device; wherein the activating comprises waking the transceiver from a low power sleep mode using a forced wakeup from the second communication device.

INCORPORATION BY REFERENCE TO RELATED APPLICATIONS

Any and all priority claims identified in the Application Data Sheet, orany correction thereto, are hereby incorporated by reference under 37CFR 1.57. This application is a continuation of U.S. application Ser.No. 17/191,172, filed Mar. 3, 2021, which is a continuation of U.S.application Ser. No. 16/925,233, filed Jul. 9, 2020, now U.S. Pat. No.10,985,804, which is a continuation of U.S. application Ser. No.16/546,099, filed Aug. 20, 2019, now abandoned, which is a continuationof U.S. application Ser. No. 15/413,206, filed Jan. 23, 2017, nowabandoned, which is a continuation of U.S. application Ser. No.13/830,330, filed Mar. 14, 2013, now U.S. Pat. No. 9,788,354, which is acontinuation of U.S. application Ser. No. 13/827,577, filed Mar. 14,2013, now U.S. Pat. No. 9,445,445. Each of the aforementionedapplications is incorporated by reference herein in its entirety, andeach is hereby expressly made a part of this specification.

FIELD

The present invention relates generally to systems and methods forprocessing, transmitting and displaying data received from an analytesensor, such as a glucose sensor.

BACKGROUND

Diabetes mellitus is a disorder in which the pancreas cannot createsufficient insulin (Type I or insulin dependent) and/or in which insulinis not effective (Type 2 or non-insulin dependent). In the diabeticstate, the victim suffers from high blood sugar, which causes an arrayof physiological derangements (kidney failure, skin ulcers, or bleedinginto the vitreous of the eye) associated with the deterioration of smallblood vessels. A hypoglycemic reaction (low blood sugar) may be inducedby an inadvertent overdose of insulin, or after a normal dose of insulinor glucose-lowering agent accompanied by extraordinary exercise orinsufficient food intake.

Conventionally, a diabetic person carries a self-monitoring bloodglucose (SMBG) monitor, which typically requires uncomfortable fingerpricking methods. Due to the lack of comfort and convenience, a diabeticwill normally only measure his or her glucose level two to four timesper day. Unfortunately, these time intervals are spread so far apartthat the diabetic will likely find out too late, sometimes incurringdangerous side effects, of a hyperglycemic or hypoglycemic condition. Infact, it is not only unlikely that a diabetic will take a timely SMBGvalue, but additionally the diabetic will not know if his blood glucosevalue is going up (higher) or down (lower) based on conventionalmethods.

Consequently, a variety of non-invasive, transdermal (e.g.,transcutaneous) and/or implantable electrochemical sensors are beingdeveloped for continuously detecting and/or quantifying blood glucosevalues. These devices generally transmit raw or minimally processed datafor subsequent analysis at a remote device, which can include a display.

SUMMARY

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

In a first aspect, a method for transmitting data between a firstcommunication device associated with an analyte sensor and a secondcommunication device configured to provide user access to sensor-relatedinformation is disclosed, the method comprising: activating atransceiver of a first communication device associated with an analytesensor at a first time; and establishing a two-way communication channelwith the second communication device; wherein the activating compriseswaking the transceiver from a low power sleep mode using a forced wakeupfrom the second communication device. In an embodiment of the firstaspect, establishing the two-way communication channel includes usingauthentication information related to the transceiver. In an embodimentof the first aspect, authentication information comprises a transmitterserial number. In an embodiment of the first aspect, the transceiver ofthe first communication device is configured to engage in near fieldcommunication (NFC) with second communication device. In an embodimentof the first aspect, the transceiver of the first communication devicecomprises an NFC tag that may be powered by the second communicationdevice. In an embodiment of the first aspect, the second communicationdevice is configured to engage in NFC with the transceiver of the firstcommunication device and wherein the second communication devicecomprises an NFC initiator. In an embodiment of the first aspect, thesecond communication device comprises a software application that allowsa user to initiate NFC with the first communication device. In anembodiment of the first aspect, the software application instructs theuser to place second communication in close proximity to the firstcommunication device. In an embodiment of the first aspect, closeproximity comprises a distance that is less than 12 inches. In anembodiment of the first aspect, close proximity comprises a distancethat is less than 6 inches. In an embodiment of the first aspect, themethod further comprises: sending sensor-related information to thesecond communication device using the two-way communication channelduring a transmission window; deactivating the transceiver of the firstcommunication device at a second time; and periodically repeating theactivating, establishing, sending and deactivating, wherein a differencebetween the first time and the second time is less than or equal to oneminute, and wherein the periodic repeating is performed at least onceevery 30 minutes. In an embodiment of the first aspect, the forcedwakeup is out of sync with the periodic activating and deactivating,causing a break in a transmission window. In an embodiment of the firstaspect, the method further comprises: sending a calibration value to thefirst communication device and receiving an updated glucose value at thesecond communication device immediately thereafter. In an embodiment ofthe first aspect, the method further comprises: sending new settinginformation to the first communication device. In an embodiment of thefirst aspect, the first communication device and second communicationdevice are paired using NFC.

In a second aspect, a method of providing a transmission pause mode isdisclosed, the method comprising: sending a transmission pause commandfrom a second communication device to a first communication device,wherein the first communication device is in communication with analytesensor circuitry. In an embodiment of the second aspect, a softwareapplication running on the second communication device prompts the userto enter the transmission pause mode, the transmission pause mode havinga reduced power level. In an embodiment of the second aspect, thetransmission pause mode is in compliance with the federal aviationadministration guidelines for electronic devices. In an embodiment ofthe second aspect, the user is requested to enter a duration of timethat the first communication device will remain in the transmissionpause mode. In an embodiment of the second aspect, the secondcommunication device deactivates the transceiver of the firstcommunication device for the transmission pause mode duration.

In a third aspect, a method for detecting sleep current in a sensordevice using a sleep current circuit in communication with the sensordevice is disclosed, the method comprising: initiating a reduced powerstate for the sensor device; providing a sleep pulse signal to acapacitor in the sleep current circuit; measuring a charge on thecapacitor in the sleep current circuit; and comparing the charge on thecapacitor to a predetermined threshold to determine if the charge on thecapacitor exceeds the predetermined threshold. In an embodiment of thethird aspect, the method further comprises: terminating the reducedpower state for the sensor device. In an embodiment of the third aspect,the measuring a charge on the capacitor is performed after the reducedpower state is terminated. In an embodiment of the third aspect, themethod further comprises: terminating the sleep pulse signal while thesensor device is in a reduced power state. In an embodiment of the thirdaspect, the method further comprises: terminating the reduced powerstate for the sensor device within 1 second of terminating the sleeppulse signal. In an embodiment of the third aspect, the sleep pulsesignal is provided to the capacitor via a switch. In an embodiment ofthe third aspect, the predetermined threshold is an expected charge onthe capacitor that correlates with the sleep pulse signal. In anembodiment of the third aspect, the sleep current is any unexpectedcurrent flowing within the sensor device while it is in the reducedpower state. In an embodiment of the third aspect, the sleep current isdetected by subtracting the predetermined threshold from the charge onthe capacitor. In an embodiment of the third aspect, the method furthercomprises: providing an error message to a user if sleep current isdetected.

In a fourth aspect, a system for measuring sleep current is disclosed,the system comprising: sensor measurement circuitry in communicationwith one or more power supply circuitry configured to provide power tothe measurement circuitry; sleep current circuitry configured to detectsleep current in the system; and control circuitry configured to provideinstructions to measurement circuitry to switch to a sleep mode andconfigured to provide a sleep pulse signal to the sleep currentcircuitry for determining if any sleep current is present in the system.In an embodiment of the fourth aspect, the sleep current circuitrycomprises a capacitor configured to collect a charge that correlateswith the sleep pulse signal. In an embodiment of the fourth aspect, thesleep current circuitry is configured to detect sleep current bycomparing the charge on the capacitor with a predetermined threshold.

In a fifth aspect, a method of providing an adjustable integrationwindow is disclosed, the method comprising: storing two or more sensordata points in a memory buffer to create an integrated data point,wherein each of the sensor data points is associated with a time stampand the stored data points define an integration window; receiving areference value associated with a time stamp; and adjusting theintegration window to correspond to the time stamp for the referencevalue. In an embodiment of the fifth aspect, the integration windowcomprises two or more sensor data points taken at 30-second timeintervals. In an embodiment of the fifth aspect, the integration windowcomprises ten sensor data points taken at 30-second time intervals. Inan embodiment of the fifth aspect, the two or more sensor data pointsare averaged to create an integrated data point. In an embodiment of thefifth aspect, wherein upon receipt of a new sensor data point, thesensor data point associated with an oldest time stamp stored in thememory buffer is deleted, and the sensor data points stored in thememory buffer and the new sensor data point are averaged to create anintegrated data point. In an embodiment of the fifth aspect, thereference value is a blood glucose value. In an embodiment of the fifthaspect, adjusting the integration window to correspond to the time stampfor the reference value comprises: selecting an even number of sensordata points having time stamps before and after the time stampassociated with the reference value; and averaging the sensor datapoints to provide an integrated data point having a close time proximityto the time stamp associated with the reference value. In an embodimentof the fifth aspect, the time proximity of the integrated data point iswithin thirty seconds of the time stamp associated with the referencevalue. In an embodiment of the fifth aspect, the sensor data pointsclosest in time to the time stamp for the reference value are moreheavily weighted than sensor data points furthest from the time stampfor the reference value in the integration window. In an embodiment ofthe fifth aspect, the integrated data point is extrapolated using one ormore sensor data points stored in the memory buffer. In an embodiment ofthe fifth aspect, the integrated data point is extrapolated to a pointof 2.5 minutes in the future using five 30-second data values stored inthe memory buffer. In an embodiment of the fifth aspect, the sensor datapoints defining the integration window are taken at a fixed timeinterval, wherein the fixed time interval is adjusted depending onsensor data information. In an embodiment of the fifth aspect, sensordata information comprises a glucose rate of change.

In a sixth aspect, a method of providing leak detection adjustment isdisclosed, the method comprising: detecting a leakage current using aleak detection circuit in communication with an analyte sensor systemhaving a processor; receiving, using the processor, the leakage currentfrom the leak detection circuit; and performing an adjustment to asensor signal using the leakage current. In an embodiment of the sixthaspect, the adjustment to the sensor signal comprises subtracting theleakage current from the sensor signal. In an embodiment of the sixthaspect, performing an adjustment to the sensor signal is performed usingthe processor of the analyte sensor system. In an embodiment of thesixth aspect, performing an adjustment to the sensor signal is performedusing an external processing device. In an embodiment of the sixthaspect, the method further comprises: providing the adjusted sensorsignal to a user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating some embodiments of a continuousanalyte sensor system including a sensor electronics module.

FIG. 2A is a block diagram of a sensor electronics module in accordancewith some embodiments.

FIG. 2B is a perspective view of the sensor electronics module of FIG.2A held in a mounting unit in accordance with some embodiments.

FIG. 2C is a side cross-sectional view of the sensor electronics moduleand mounting unit of FIG. 2B in accordance with some embodiments.

FIG. 3 is an exemplary block diagram illustrating various elements ofsome embodiments of a continuous analyte sensor system and displaydevice.

FIG. 4A is a schematic circuit diagram of a low power measurementcircuit in accordance with some embodiments.

FIG. 4B is a schematic circuit diagram of a sleep current measurementcircuit in accordance with some embodiments.

FIG. 4C is a sleep timing graph for the circuit of FIG. 4A in accordancewith some embodiments.

FIG. 5A is a simplified block diagram of an embodiment of sensorelectronics module with a low power storage mode feature.

FIG. 5B is a flow chart of an exemplary process for placing sensorelectronics module into a storage mode and taking sensor electronicsmodule out of the storage mode.

FIG. 6 illustrates an embodiment of a split connector having an axialsymmetric layout in accordance with some embodiments.

FIG. 7 illustrates an embodiment of a split connector having aconcentric layout in accordance with some embodiments.

FIG. 8 is a schematic cross-sectional view of a sensor electronicsmodule attached to a mounting unit in accordance with some embodiments.

FIG. 9A is a flow diagram of an exemplary communication between ananalyte sensor system and a display device for communicating glucosemeasurement values.

FIG. 9B is a timing diagram of en exemplary sequence for establishing acommunication channel between an analyte sensor system and a displaydevice.

FIG. 10 is a flowchart of an exemplary method for sending glucosemeasurement values from an analyte sensor system to a display device.

DETAILED DESCRIPTION

The following description and examples illustrate some exemplaryembodiments of the disclosed invention in detail. Those of skill in theart will recognize that there are numerous variations and modificationsof this invention that are encompassed by its scope. Accordingly, thedescription of a certain exemplary embodiment should not be deemed tolimit the scope of the present invention.

Definitions

In order to facilitate an understanding of the systems and methodsdiscussed herein, a number of terms are defined below. The terms definedbelow, as well as other terms used herein, should be construed toinclude the provided definitions, the ordinary and customary meaning ofthe terms, and any other implied meaning for the respective terms. Thus,the definitions below do not limit the meaning of these terms, but onlyprovide exemplary definitions.

The terms “processor module,” “microprocessor” and “processor” as usedherein are broad terms and are to be given their ordinary and customarymeaning to a person of ordinary skill in the art, and furthermore referwithout limitation to a computer system, state machine, and the likethat performs arithmetic and logic operations using logic circuitry thatresponds to and processes the basic instructions that drive a computer.

The terms “sensor data”, as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art, and furthermore refers without limitation to any dataassociated with a sensor, such as a continuous analyte sensor. Sensordata includes a raw data stream, or simply data stream, of analog ordigital signal directly related to a measured analyte from an analytesensor (or other signal received from another sensor), as well ascalibrated and/or filtered raw data. In one example, the sensor datacomprises digital data in “counts” converted by an A/D converter from ananalog signal (e.g., voltage or amps) and includes one or more datapoints representative of a glucose concentration. Thus, the terms“sensor data point” and “data point” refer generally to a digitalrepresentation of sensor data at a particular time. The term broadlyencompasses a plurality of time spaced data points from a sensor, suchas a from a substantially continuous glucose sensor, which comprisesindividual measurements taken at time intervals ranging from fractionsof a second up to, e.g., 1, 2, or 5 minutes or longer. In anotherexample, the sensor data includes an integrated digital valuerepresentative of one or more data points averaged over a time period.Sensor data may include calibrated data, smoothed data, filtered data,transformed data, and/or any other data associated with a sensor.

The term “algorithm” as used herein is a broad term and is to be givenits ordinary and customary meaning to a person of ordinary skill in theart, and furthermore refers without limitation to a computationalprocess (associated with computer programming or other writteninstructions) involved in transforming information from one state toanother.

The term “sensor” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art,and furthermore refers without limitation to any device (or portion of adevice) that measures a physical quantity and converts it into a signalthat can be processed by analog and/or digital circuitry. Thus, theoutput of a sensor may be an analog and/or digital signal. Examples ofsensors include analyte sensors, glucose sensors, temperature sensors,altitude sensors, accelerometers, and heart rate sensors.

The terms “coupled”, “operably connected” and “operably linked” as usedherein are broad terms and are to be given their ordinary and customarymeaning to a person of ordinary skill in the art, and furthermore referwithout limitation to one or more components being linked to anothercomponent(s), either directly or indirectly, in a manner that allowstransmission of signals between the components. For example, modules ofa computing device that communicate via a common data bus are coupled toone another. As another example, one or more electrodes of a glucosesensor can be used to detect the amount of glucose in a sample andconvert that information into a signal, e.g., an electrical orelectromagnetic signal; the signal can then be transmitted to anelectronic circuit. In this case, the electrode is “operably linked” tothe electronic circuitry, even though the analog signal from theelectrode is transmitted and/or transformed by analog and/or digitalcircuitry before reaching the electronic circuit. These terms are broadenough to include wireless connectivity.

The term “physically connected” as used herein is a broad term and is tobe given its ordinary and customary meaning to a person of ordinaryskill in the art, and furthermore refers without limitation to one ormore components that are connected to another component(s) throughdirect contact and/or a wired connection, including connecting via oneor more intermediate physically connecting component(s). For example, aglucose sensor may be physically connected to a sensor electronicsmodule, and thus the processor module located therein, either directlyor via one or more electrical connections.

The term “continuous analyte sensor” as used herein is a broad term andis to be given its ordinary and customary meaning to a person ofordinary skill in the art, and furthermore refers without limitation toa device, or portion of a device, that continuously or continuallymeasures a concentration of an analyte, for example, at time intervalsranging from fractions of a second up to, for example, 1, 2, or 5minutes, or longer. In one exemplary embodiment, a glucose sensorcomprises a continuous analyte sensor, such as is described in U.S. Pat.No. 7,310,544, which is incorporated herein by reference in itsentirety.

The term “sensor session” as used herein, is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art, and refers without limitation to a period of time a sensoris in use, such as but not limited to a period of time starting at thetime the sensor is implanted (e.g., by the host) to removal of thesensor (e.g., removal of the sensor from the host's body and/or removalof the sensor electronics module from the sensor housing).

The term “sensor information” as used herein is a broad term, and is tobe given its ordinary and customary meaning to a person of ordinaryskill in the art, and furthermore refers without limitation toinformation associated with measurement, signal processing (includingcalibration), alarms, data transmission, and/or display associated witha sensor, such as a continuous analyte sensor. The term is broad enoughto include raw sensor data (one or more raw analyte concentrationvalues), as well as transformed sensor data. In some embodiments, sensorinformation includes displayable sensor information.

The term “displayable sensor information” as used herein is a broadterm, and is to be given its ordinary and customary meaning to a personof ordinary skill in the art, and furthermore refers without limitationto information that is transmitted for display on one or more displaydevices. As is discussed elsewhere herein, the content of displayablesensor information that is transmitted to a particular display devicemay be customized for the particular display device. Additionally,formatting of displayable sensor information may be customized forrespective display devices. Displayable sensor information may includeany sensor data, including raw sensor data, transformed sensor data,and/or any information associated with measurement, signal processing(including calibration), and/or alerts associated with one or moresensors.

The term “data package” as used herein is a broad term, and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art, and furthermore refers without limitation to a combinationof data that is transmitted to one or more display devices, such as inresponse to triggering of an alert. A data package may includedisplayable sensor information (e.g., that has been selected andformatted for a particular display device) as well as headerinformation, such as data indicating a delivery address, communicationprotocol, etc. Depending on the embodiment, a data package may comprisesmultiple packets of data that are separately transmitted to a displaydevice (and reassembled at the display device) or a single block of datathat is transmitted to the display device. Data packages may beformatted for transmission via any suitable communication protocol,including radio frequency, Bluetooth, universal serial bus, any of thewireless local area network (WLAN) communication standards, includingthe IEEE 802.11, 802.15, 802.20, 802.22 and other 802 communicationprotocols, and/or a proprietary communication protocol.

The term “direct wireless communication” as used herein is a broad term,and is to be given its ordinary and customary meaning to a person ofordinary skill in the art, and furthermore refers without limitation toa data transmission that goes from one device to another device withoutany intermediate data processing (e.g., data manipulation). For example,direct wireless communication between a sensor electronics module and adisplay device occurs when the sensor information transmitted from thesensor electronics module is received by the display device withoutintermediate processing of the sensor information. The term is broadenough to include wireless communication that is transmitted through arouter, a repeater, a telemetry receiver (e.g., configured tore-transmit the sensor information without additional algorithmicprocessing), and the like. The term is also broad enough to includetransformation of data format (e.g., via a Bluetooth receiver) withoutsubstantive transformation of the sensor information itself.

Overview

In some embodiments, a system is provided for continuous measurement ofan analyte in a host that includes: a continuous analyte sensorconfigured to continuously measure a concentration of the analyte in thehost and a sensor electronics module physically connected to thecontinuous analyte sensor during sensor use. In some embodiments, thesensor electronics module includes electronics configured to process adata stream associated with an analyte concentration measured by thecontinuous analyte sensor in order to generate sensor information thatincludes raw sensor data, transformed sensor data, and/or any othersensor data, for example. The sensor electronics module may further beconfigured to generate sensor information that is customized forrespective display devices, such that different display devices mayreceive different sensor information.

Display Devices

In some embodiments, the sensor electronics module is configured tosearch for and/or attempt wireless communication with a display devicefrom a list of display devices. In some embodiments, the sensorelectronics module is configured to search for and/or attempt wirelesscommunication with a list of display devices in a predetermined and/orprogrammable order (e.g., grading and/or escalating), for example,wherein a failed attempt at communication with and/or alarming with afirst display device triggers an attempt at communication with and/oralarming with a second display device, and so on.

Depending on the embodiment, one or more display devices that receivedata packages from the sensor electronics module are “dummy displays”,wherein they display the displayable sensor information received fromthe sensor electronics module without additional processing (e.g.,prospective algorithmic processing necessary for real-time display ofsensor information). In some embodiments, the displayable sensorinformation comprises transformed sensor data that does not requireprocessing by the display device prior to display of the displayablesensor information. Some display devices may comprise software includingdisplay instructions (software programming comprising instructionsconfigured to display the displayable sensor information and optionallyquery the sensor electronics module to obtain the displayable sensorinformation) configured to enable display of the displayable sensorinformation thereon. In some embodiments, the display device isprogrammed with the display instructions at the manufacturer and caninclude security and/or authentication to avoid plagiarism of thedisplay device. In some embodiments, a display device is configured todisplay the displayable sensor information via a downloadable program(for example, a downloadable Java Script via the internet), such thatany display device that supports downloading of a program (for example,any display device that supports Java applets) therefore can beconfigured to display displayable sensor information (e.g., mobilephones, PDAs, PCs and the like).

In some embodiments, certain display devices may be in direct wirelesscommunication with the sensor electronics module, however intermediatenetwork hardware, firmware, and/or software can be included within thedirect wireless communication. In some embodiments, a repeater (e.g., aBluetooth repeater) can be used to re-transmit the transmitteddisplayable sensor information to a location farther away than theimmediate range of the telemetry module of the sensor electronicsmodule, wherein the repeater enables direct wireless communication whensubstantive processing of the displayable sensor information does notoccur. In some embodiments, a receiver (e.g., Bluetooth receiver) can beused to re-transmit the transmitted displayable sensor information,possibly in a different format, such as in a text message onto a TVscreen, wherein the receiver enables direct wireless communication whensubstantive processing of the sensor information does not occur. In someembodiments, the sensor electronics module directly wirelessly transmitsdisplayable sensor information to one or a plurality of display devices,such that the displayable sensor information transmitted from the sensorelectronics module is received by the display device withoutintermediate processing of the displayable sensor information.

In some embodiments, one or more display devices comprise built-inauthentication mechanisms, wherein authentication is required forcommunication between the sensor electronics module and the displaydevice. In some embodiments, to authenticate the data communicationbetween the sensor electronics module and display devices, achallenge-response protocol, such as a password authentication isprovided, where the challenge is a request for the password and thevalid response is the correct password, such that pairing of the sensorelectronics module with the display devices can be accomplished by theuser and/or manufacturer via the password. However, any knownauthentication system or method useful for telemetry devices can beused.

In some embodiments, one or more display devices are configured to querythe sensor electronics module for displayable sensor information,wherein the display device acts as a master device requesting sensorinformation from the sensor electronics module (e.g., a slave device)on-demand, for example, in response to a query. In some embodiments, thesensor electronics module is configured for periodic, systematic,regular, and/or periodic transmission of sensor information to one ormore display devices (for example, every 1, 2, 5, or 10 minutes ormore). In some embodiments, the sensor electronics module is configuredto transmit data packages associated with a triggered alert (e.g.,triggered by one or more alert conditions). However, any combination ofthe above described statuses of data transmission can be implementedwith any combination of paired sensor electronics module and displaydevice(s). For example, one or more display devices can be configuredfor querying the sensor electronics module database and for receivingalarm information triggered by one or more alarm conditions being met.Additionally, the sensor electronics module can be configured forperiodic transmission of sensor information to one or more displaydevices (the same or different display devices as described in theprevious example), whereby a system can include display devices thatfunction differently with regard to how they obtain sensor information.

In some embodiments, as described in more detail elsewhere herein, adisplay device is configured to query the data storage memory in thesensor electronics module for certain types of data content, includingdirect queries into a database in the sensor electronics module's memoryand/or requests for configured or configurable packages of data contenttherefrom; namely, the data stored in the sensor electronics module isconfigurable, queryable, predetermined, and/or pre-packaged, based onthe display device with which the sensor electronics module iscommunicating. In some additional or alternative embodiments, the sensorelectronics module generates the displayable sensor information based onits knowledge of which display device is to receive a particulartransmission. Additionally, some display devices are capable ofobtaining calibration information and wirelessly transmitting thecalibration information to the sensor electronics module, such asthrough manual entry of the calibration information, automatic deliveryof the calibration information, and/or an integral reference analytemonitor incorporated into the display device. U.S. Patent PublicationNos. 2006/0222566, 2007/0203966, 2007/0208245, and 2005/0154271, all ofwhich are incorporated herein by reference in their entirety, describesystems and methods for providing an integral reference analyte monitorincorporated into a display device and/or other calibration methods thatcan be implemented with the disclosed embodiments.

In general, a plurality of display devices (e.g., a small (key fob)display device, a larger (hand-held) display device, a mobile phone, areference analyte monitor, a drug delivery device, a medical device anda personal computer) are configured to wirelessly communicate with thesensor electronics module, wherein the one or more display devices areconfigured to display at least some of the displayable sensorinformation wirelessly communicated from the sensor electronics module,wherein displayable sensor information includes sensor data, such as rawdata and/or transformed sensor data, such as analyte concentrationvalues, rate of change information, trend information, alertinformation, sensor diagnostic information and/or calibrationinformation, for example.

Small (Key Fob) Display Device

In some embodiments, one the plurality of display devices is a small(e.g., key fob) display device 14 a (FIG. 1) that is configured todisplay at least some of the sensor information, such as an analyteconcentration value and a trend arrow. In general, a key fob device is asmall hardware device with a built-in authentication mechanism sized tofit on a key chain. However, any small display device 14 a can beconfigured with the functionality as described herein with reference tothe key fob device 14 a, including a wrist band, a hang tag, a belt, anecklace, a pendent, a piece of jewelry, an adhesive patch, a pager, anidentification (ID) card, and the like, all of which are included by thephrase “small display device” and/or “key fob device” herein.

In general, the key fob device 14 a includes electronics configured toreceive and display displayable sensor information. In some embodiments,the electronics include a RAM and a program storage memory configured atleast to display the sensor data received from the sensor electronicsmodule. In some embodiments, the key fob device 14 a includes an alarmconfigured to warn a host of a triggered alert (e.g., audio, visualand/or vibratory). In some embodiments, the key fob device 14 a includesa user interface, such as an LCD 602 and one or more buttons 604 thatallows a user to view data, such as a numeric value and/or an arrow, totoggle through one or more screens, to select or define one or more userparameters, to respond to (e.g., silence, snooze, turn off) an alert,and/or the like.

In some embodiments, the key fob display device has a memory (e.g., suchas in a gig stick or thumb drive) that stores sensor, drug (e.g.,insulin) and other medical information, enabling a memory stick-typefunction that allows data transfer from the sensor electronics module toanother device (e.g., a PC) and/or as a data back-up location for thesensor electronics module memory (e.g., data storage memory). In someembodiments, the key fob display device is configured to beautomatically readable by a network system upon entry into a hospital orother medical complex.

In some embodiments, the key fob display device includes a physicalconnector, such as USB port 606, to enable connection to a port (e.g.,USB) on a computer, enabling the key fob to function as a data downloaddevice (e.g., from the sensor electronics module to a PC), a telemetryconnector (e.g., Bluetooth adapter/connector for a PC), and/or enablesconfigurable settings on the key fob device (e.g., via software on thePC that allows configurable parameters such as numbers, arrows, trend,alarms, font, etc.). In some embodiments, user parameters associatedwith the small (key fob) display device can be programmed into (and/ormodified) by a display device such as a personal computer, personaldigital assistant, or the like. In some embodiments, user parametersinclude contact information, alert/alarms settings (e.g., thresholds,sounds, volume, and/or the like), calibration information, font size,display preferences, defaults (e.g., screens), and/or the like.Alternatively, the small (key fob) display device can be configured fordirect programming of user parameters. In some embodiments, wherein thesmall (key fob) display device comprises a telemetry module, such asBluetooth, and a USB connector (or the like), such that the small (keyfob) display device additionally functions as telemetry adapter (e.g.,Bluetooth adapter) enabling direct wireless communication between thesensor electronics module and the PC, for example, wherein the PC doesnot include the appropriate telemetry adapter therein.

Large (Hand-held) Display Device

In some embodiments, one the plurality of display devices is a hand-helddisplay device 14 b (FIG. 1) configured to display sensor informationincluding an analyte concentration and a graphical representation of theanalyte concentration over time. In general, the hand-held displaydevice comprises a display 608 sufficiently large to display a graphicalrepresentation 612 of the sensor data over a time period, such as aprevious 1, 3, 5, 6, 9, 12, 18, or 24-hours of sensor data. In someembodiments, the hand-held device 14 b is configured to display a trendgraph or other graphical representation, a numeric value, an arrow,and/or to alarm the host. U.S. Patent Publication No. 2005/0203360,which is incorporated herein by reference in its entirety, describes andillustrates some examples of display of data on a hand-held displaydevice. Although FIG. 1 illustrates some embodiments of a hand-helddisplay device 14 b, the hand-held device can be any single applicationdevice or multi-application device, such as mobile phone, a palm-topcomputer, a PDA, portable media player (e.g., iPod, MP3 player), a bloodglucose meter, an insulin pump, and/or the like.

In some embodiments, a mobile phone (or PDA) 14 c is configured todisplay (as described above) and/or relay sensor information, such asvia a voice or text message to the host and/or the host's care provider.In some embodiments, the mobile phone 14 c further comprises an alarmconfigured to warn a host of a triggered alert, such as in response toreceiving a data package indicating triggering of the alert. Dependingon the embodiment, the data package may include displayable sensorinformation, such as an on-screen message, text message, and/orpre-generated graphical representation of sensor data and/or transformedsensor data, as well as an indication of an alarm, such as an auditoryalarm or a vibratory alarm, that should be activated by the mobilephone.

In some embodiments, one of the display devices is a drug deliverydevice, such as an insulin pump and/or insulin pen, configured todisplay sensor information. In some embodiments, the sensor electronicsmodule is configured to wirelessly communicate sensor diagnosticinformation to the drug delivery device in order to enable to the drugdelivery device to consider (include in its calculations/algorithms) aquality, reliability and/or accuracy of sensor information for closedloop and/or semi-closed loop systems, which are described in more detailin U.S. Patent Publication No. 2005/0192557, which is incorporatedherein by reference in its entirety. In some alternative embodiments,the sensor electronic module is configured to wirelessly communicatewith a drug delivery device that does not include a display, forexample, in order to enable a closed loop and/or semi-closed loop systemas described above.

In some embodiments, one of the display devices is a drug deliverydevice is a reference analyte monitor, such as a blood glucose meter,configured to measure a reference analyte value associated with ananalyte concentration in a biological sample from the host.

Personal Computer Display Device

In some embodiments, one of the display devices is personal computer(PC) 14 d (FIG. 1) configured to display sensor information. Preferably,the PC 14 d has software installed, wherein the software enables displayand/or performs data analysis (retrospective processing) of the historicsensor information. In some embodiments, a hardware device can beprovided (not shown), wherein the hardware device (e.g., dongle/adapter)is configured to plug into a port on the PC to enable wirelesscommunication between the sensor electronics module and the PC. In someembodiments, the PC 14 d is configured to set and/or modify configurableparameters of the sensor electronics module 12 and/or small (key fobdevice) 14 a, as described in more detail elsewhere herein.

Other Display Devices

In some embodiments, one of the display devices is an on-skin displaydevice that is splittable from, releasably attached to, and/or dockableto the sensor housing (mounting unit, sensor pod, or the like). In someembodiments, release of the on-skin display turns the sensor off; inother embodiments, the sensor housing comprises sufficient sensorelectronics to maintain sensor operation even when the on-skin displayis released from the sensor housing.

In some embodiments, one of the display devices is a secondary device,such as a heart rate monitor, a pedometer, a temperature sensor, a carinitialization device (e.g., configured to allow or disallow the car tostart and/or drive in response to at least some of the sensorinformation wirelessly communicated from the sensor electronics module(e.g., glucose value above a predetermined threshold)). In somealternative embodiments, one of the display devices is designed for analternative function device (e.g., a caller id device), wherein thesystem is configured to communicate with and/or translate displayablesensor information to a custom protocol of the alternative device suchthat displayable sensor information can be displayed on the alternativefunction device (display of caller id device).

Exemplary Configurations

FIG. 1 is a diagram illustrating some embodiments of a continuousanalyte sensor system 8 including a sensor electronics module 12. In theembodiment of FIG. 1, the system includes a continuous analyte sensor 10physically connected to a sensor electronics module 12, which is indirect wireless communication with a plurality of different displaydevices 14.

In some embodiments, the sensor electronics module 12 includeselectronic circuitry associated with measuring and processing thecontinuous analyte sensor data, including prospective algorithmsassociated with processing and calibration of the sensor data. Thesensor electronics module 12 may be physically connected to thecontinuous analyte sensor 10 and can be integral with (non-releasablyattached to) or releasably attachable to the continuous analyte sensor10. The sensor electronics module 12 may include hardware, firmware,and/or software that enables measurement of levels of the analyte via aglucose sensor, such as an analyte sensor. For example, the sensorelectronics module 12 can include a potentiostat, a power source forproviding power to the sensor, other components useful for signalprocessing and data storage, and a telemetry module for transmittingdata from the sensor electronics module to one or more display devices.Electronics can be affixed to a printed circuit board (PCB), or thelike, and can take a variety of forms. For example, the electronics cantake the form of an integrated circuit (IC), such as anApplication-Specific Integrated Circuit (ASIC), a microcontroller,and/or a processor. The sensor electronics module 12 includes sensorelectronics that are configured to process sensor information, such assensor data, and generate transformed sensor data and displayable sensorinformation. Examples of systems and methods for processing sensoranalyte data are described in more detail herein and in U.S. Pat. Nos.7,310,544 and 6,931,327 and U.S. Patent Publication Nos. 2005/0043598,2007/0032706, 2007/0016381, 2008/0033254, 2005/0203360, 2005/0154271,2005/0192557, 2006/0222566, 2007/0203966 and 2007/0208245, all of whichare incorporated herein by reference in their entirety.

Referring again to FIG. 1, a plurality of display devices 14 areconfigured for displaying (and/or alarming) the displayable sensorinformation that has been transmitted by the sensor electronics module12 (e.g., in a customized data package that is transmitted to thedisplay devices based on their respective preferences). For example, thedisplay devices are configured to display the displayable sensorinformation as it is communicated from the sensor electronics module(e.g., in a data package that is transmitted to respective displaydevices), without any additional prospective processing required forcalibration and real-time display of the sensor data.

Because different display devices provide different user interfaces,content of the data packages (e.g., amount, format, and/or type of datato be displayed, alarms, and the like) can be customized (e.g.,programmed differently by the manufacture and/or by an end user) foreach particular display device. Accordingly, in the embodiment of FIG.1, a plurality of different display devices are in direct wirelesscommunication with the sensor electronics module (e.g., such as anon-skin sensor electronics module 12 that is physically connected to thecontinuous analyte sensor 10) during a sensor session to enable aplurality of different types and/or levels of display and/orfunctionality associated with the displayable sensor information, whichis described in more detail elsewhere herein.

Continuous Sensor

In some embodiments, a glucose sensor comprises a continuous sensor, forexample a subcutaneous, transdermal (e.g., transcutaneous), orintravascular device. In some embodiments, the device can analyze aplurality of intermittent blood samples. The glucose sensor can use anymethod of glucose-measurement, including enzymatic, chemical, physical,electrochemical, spectrophotometric, polarimetric, calorimetric,iontophoretic, radiometric, immunochemical, and the like.

A glucose sensor can use any known method, including invasive, minimallyinvasive, and non-invasive sensing techniques (e.g., fluorescentmonitoring), to provide a data stream indicative of the concentration ofglucose in a host. The data stream is typically a raw data signal, whichis converted into a calibrated and/or filtered data stream that is usedto provide a useful value of glucose to a user, such as a patient or acaretaker (e.g., a parent, a relative, a guardian, a teacher, a doctor,a nurse, or any other individual that has an interest in the wellbeingof the host).

A glucose sensor can be any device capable of measuring theconcentration of glucose. One exemplary embodiment is described below,which utilizes an implantable glucose sensor. However, it should beunderstood that the devices and methods described herein can be appliedto any device capable of detecting a concentration of glucose andproviding an output signal that represents the concentration of glucose.

In some embodiments, the analyte sensor is an implantable glucosesensor, such as described with reference to U.S. Pat. No. 6,001,067 andU.S. Patent Publication No. US-2005-0027463-A1. In another embodiment,the analyte sensor is a transcutaneous glucose sensor, such as describedwith reference to U.S. Patent Publication No. US-2006-0020187-A1. Instill other embodiments, the sensor is configured to be implanted in ahost vessel or extracorporeally, such as is described in U.S. PatentPublication No. US-2007-0027385-A1, U.S. Patent Publication No.US-2008-0119703-A1, U.S. Patent Publication No. US-2008-0108942-A1, andU.S. Pat. No. 7,828,728. In one alternative embodiment, the continuousglucose sensor comprises a transcutaneous sensor such as described inU.S. Pat. No. 6,565,509 to Say et al., for example. In anotheralternative embodiment, the continuous glucose sensor comprises asubcutaneous sensor such as described with reference to U.S. Pat. No.6,579,690 to Bonnecaze et al. or U.S. Pat. No. 6,484,046 to Say et al.,for example. In another alternative embodiment, the continuous glucosesensor comprises a refillable subcutaneous sensor such as described withreference to U.S. Patent 6,12,939 to Colvin et al., for example. Inanother alternative embodiment, the continuous glucose sensor comprisesan intravascular sensor such as described with reference to U.S. Pat.No. 6,477,395 to Schulman et al., for example. In another alternativeembodiment, the continuous glucose sensor comprises an intravascularsensor such as described with reference to U.S. Pat. No. 6,424,847 toMastrototaro et al., for example.

Sensor Electronics Module

FIG. 2A is a block diagram illustrating embodiments of the sensorelectronics module 12 (FIG. 1). The sensor electronics module 12 caninclude an application-specific integrated circuit (ASIC) 205, a userinterface 222, compression sensor 254 and temperature sensor 252. ASIC205 can also be coupled to a communication port 238 and a battery 234.Although FIG. 2A shows an ASIC 205 that includes much of the electroniccircuitry, the ASIC 205 may be replaced with one or more of any suitablelogic device, such as field programmable gate arrays (FPGA),microprocessors, analog circuitry, or other digital and/or analogcircuitry. Further, ASIC 205 can include one or more additional featuresof sensor electronics module 12 discussed elsewhere herein, or one ormore features illustrated in FIG. 2A as being part of the ASIC—such astelemetry module 232, potentiostat 210, data storage memory 220—can beseparate from the ASIC.

In this embodiment, a potentiostat 210 is coupled to a glucose sensorvia data line 212, for example, in order to receive sensor data from theglucose sensor. In some embodiments, the potentiostat 210 provides avoltage to the glucose sensor via a data line 212 in order to bias thesensor to enable measurement of a current value indicative of theanalyte concentration in the host (also referred to as the analogportion). The potentiostat can have one channel or multiple channels(and a corresponding one or multiple data lines 212), depending on thenumber of working electrodes, for example. In some embodiments, thepotentiostat 210 includes a resistor (not shown) that translates thecurrent into voltage. In some embodiments, a current to frequencyconverter is provided that is configured to continuously integrate themeasured current, for example, using a charge counting device. In someembodiments, an A/D converter digitizes the analog signal into “counts”for processing. Accordingly, the resulting raw data stream in counts isdirectly related to the current measured by the potentiostat 210.

A processor module 214 is the central control unit that controls theprocessing of the sensor electronics module 12. In some embodiments, theprocessor module 214 is formed as part of a custom chip, such as anASIC, however a computer system other than an ASIC can be used toprocess data as described herein, for example a microprocessor can beused for some or all of the sensor electronics module processing. Theprocessor module 214 typically provides a program memory 216, whichprovides semi-permanent storage of data, for example, storing data suchas sensor identifier (ID) and programming to process data streams (forexample, filtering, calibration, fail-safe checking, and the like). Theprocessor additionally can be used for the system's cache memory, forexample for temporarily storing recent sensor data. In some embodiments,the processor module comprises memory storage components such as ROM,RAM, dynamic-RAM, static-RAM, non-static RAM, EEPROM, rewritable ROMs,flash memory, and the like. In one exemplary embodiment, RAM 218 can beused for the system's cache memory, for example for temporarily storingrecent sensor data.

In some embodiments, the processor module 214 comprises a digitalfilter, for example, an BR or FIR filter, configured to smooth the rawdata stream from the A/D converter. Generally, digital filters areprogrammed to filter data sampled at a predetermined time interval (alsoreferred to as a sample rate). In some embodiments, such as when thepotentiostat 210 is configured to measure the analyte at discrete timeintervals, these time intervals determine the sample rate of the digitalfilter. In some alternative embodiments, wherein the potentiostat 210 isconfigured to continuously measure the analyte, for example, using acurrent-to-frequency converter, the processor module 214 can beprogrammed to request a digital value from the integrator at apredetermined time interval, also referred to as the acquisition time.In these alternative embodiments, the values obtained by the processormodule 214 are advantageously averaged over the acquisition time due thecontinuity of the current measurement. Accordingly, the acquisition timedetermines the sample rate of the digital filter.

In an embodiment, the processor module 214 may be further configured togenerate data packages for transmission to one or more display devices.Furthermore, the processor module 215 may generate data packets fortransmission to these outside sources, e.g., via telemetry. As discussedabove, the data packages may be customizable for each display device,for example, and may include any available data, such as displayablesensor information having customized sensor data and/or transformedsensor data, sensor/sensor electronics module ID code, raw data,filtered data, calibrated data, rate of change information, trendinformation, error detection or correction, and/or the like.

A data storage memory 220 is operably connected to the processor module214 and is configured to store a variety of sensor information. In someembodiments, the data storage memory stores 1, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 20, 30 or more days of continuous analyte sensordata. In some embodiments, the data storage memory 220 stores sensorinformation such as raw sensor data (one or more raw analyteconcentration values), calibrated data, filtered data, transformedsensor data, and/or any other displayable sensor information.

In some embodiments, sensor electronics module 12 is configured toreceive and store contact information in the data storage memory (and/orprogram memory), including a phone number and/or email address for thesensor's host and/or health care providers for the host (e.g., familymember(s), nurse(s), doctor(s), or other health care provider(s)), whichenables communication with a contact person (e.g., via phone, pagerand/or text messaging in response to an alarm (e.g., a hypoglycemicalarm that has not been responded to by the host)). In some embodiments,user parameters can be programmed into (and/or modified in) the datastorage memory (and/or program memory) of the sensor electronics module,via a display device such as a personal computer, personal digitalassistant, or the like. Preferably, user parameters include contactinformation, alert/alarms settings (e.g., thresholds, sounds, volume,and/or the like), calibration information, font size, displaypreferences, defaults (e.g., screens), and/or the like. Alternatively,the sensor electronics module can be configured for direct programmingof certain user parameters.

In one embodiment, clinical data of a medical practitioner may beuploaded to the sensor electronics module 12 and stored on the datastorage memory 220, for example. Thus, information regarding the host'scondition, treatments, medications, etc., may be stored on the sensorelectronics module 12 and may be viewable by the host or otherauthorized user. In some embodiments, certain of the clinical data maybe included in a data package that is transmitted to a display device inresponse to triggering of an alert. The clinical data may be uploaded tothe sensor electronics module 12 via any available communicationprotocol, such as direct transmission via a wireless Bluetooth,infrared, or RF connection, or via a wired USB connection, for example.Additionally, the clinical data may be uploaded to the sensorelectronics module 12 via indirect transmission, such as via one or morenetworks (e.g.,. local area, personal area, or wide area networks, orthe Internet) or via a repeater device that receives the clinical datafrom a device of the medical practitioner and retransmits the clinicaldata to the sensor electronics module.

Although separate data storage 220 and program memory 216 are shown inFIG. 2A, one skilled in the art appreciates a variety of configurations,including one or multiple memories that provide the necessary storagespace to support the sensor electronic module 12 data processing andstorage requirements. Accordingly, the described location of storage ofany particular information and/or or programming is not meant to belimiting, but rather exemplary.

In some embodiments, the sensor electronics module 12 is configured toperform smoothing and/or filtering algorithms on the sensor data (e.g.,raw data stream and/or other sensor information), wherein the smoothedand/or filtered data is stored in the data storage memory as transformeddata. U.S. Patent Publication No. US-2005-0043598-A1, U.S. PatentPublication No. US-2007-0032706-A1, U.S. Patent Publication No.US-2007-0016381-A1 and U.S. Patent Publication No. US-2008-0033254-A1describe some algorithms useful in performing data smoothing and/orfiltering herein (including signal artifacts replacement), and areincorporated herein by reference in their entirety.

In some embodiments, the sensor electronics module 12 is configured tocalibrate the sensor data, and the data storage memory 220 stores thecalibrated sensor data points as transformed sensor data. In somefurther embodiments, the sensor electronics module 12 is configured towirelessly receive calibration information from a display device, fromwhich the sensor electronics module is configured to calibrate thesensor data. U.S. Pat. Nos. 7,310,544 and 6,931,327 describe somealgorithms useful in sensor calibration herein, and are incorporatedherein by reference in their entirety.

In some embodiments, the sensor electronics module 12 is configured toperform additional algorithmic processing on the sensor data (e.g.,calibrated and/or filtered data and/or other sensor information) and thedata storage memory 220 is configured to store the transformed sensordata and/or sensor diagnostic information associated with thealgorithms. U.S. Pat. Nos. 7,310,544 and 6,931,327 describe somealgorithms that can be processed by the sensor electronics module, andare incorporated herein by reference in their entirety.

Referring again to FIG. 2A, a user interface 222 can include a varietyof interfaces, such as one or more buttons 224, a liquid crystal display(LCD) 226, a vibrator 228, an audio transducer (e.g., speaker) 230,backlight, and/or the like. A backlight can be provided, for example, toaid the user in reading the LCD in low light conditions. The componentsthat comprise the user interface 222 provide controls to interact withthe user (e.g., the host). One or more buttons 224 can allow, forexample, toggle, menu selection, option selection, status selection,yes/no response to on-screen questions, a “turn off” function (e.g., foran alarm), a “snooze” function (e.g., for an alarm), a reset, and/or thelike. The LCD 226 can be provided, for example, to provide the user withvisual data output. The audio transducer 230 (e.g., speaker) providesaudible signals in response to triggering of certain alerts, such aspresent and/or predicted hyper- and hypoglycemic conditions. In someembodiments, audible signals are differentiated by tone, volume, dutycycle, pattern, duration, and/or the like. In some embodiments, theaudible signal is configured to be silenced (e.g., snoozed or turnedoff) by pressing one or more buttons 224 on the sensor electronicsmodule and/or by signaling the sensor electronics module using a buttonor selection on a display device (e.g., key fob, cell phone, and/or thelike).

A telemetry module 232 is operably connected to the processor module 214and provides the hardware, firmware, and/or software that enablewireless communication between the sensor electronics module 12 and oneor more display devices. A variety of wireless communicationtechnologies that can be implemented in the telemetry module 232 includeradio frequency (RF), infrared (IR), Bluetooth, spread spectrumcommunication, frequency hopping communication, ZigBee, IEEE802.11/802.16, wireless (e.g., cellular) telecommunication, pagingnetwork communication, magnetic induction, satellite data communication,GPRS, ANT, and/or the like. In one preferred embodiment, the telemetrymodule comprises a Bluetooth chip. In some embodiments, Bluetoothtechnology is implemented in a combination of the telemetry module 232and the processor module 214.

A battery 234 is operatively connected to the processor module 214 (andpossibly other components of the sensor electronics module 12) andprovides the necessary power for the sensor electronics module 12. Insome embodiments, the battery is a Lithium Manganese Dioxide battery,however any appropriately sized and powered battery can be used (e.g.,AAA, Nickel-cadmium, Zinc-carbon, Alkaline, Lithium, Nickel-metalhydride, Lithium-ion, Zinc-air, Zinc-mercury oxide, Silver-zinc, orhermetically-sealed). In some embodiments the battery is rechargeable.In some embodiments, a plurality of batteries can be used to power thesystem. In yet other embodiments, the receiver can be transcutaneouslypowered via an inductive coupling, for example.

A battery charger and/or regulator 236 may be configured to receiveenergy from an internal and/or external charger. In some embodiments, abattery regulator (or balancer) 236 regulates the recharging process bybleeding off excess charge current to allow all cells or batteries inthe sensor electronics module to be fully charged without overchargingother cells or batteries. In some embodiments, the battery 234 (orbatteries) is configured to be charged via an inductive and/or wirelesscharging pad. One skilled in the art appreciates a variety of knownmethods of charging batteries, which can be implemented with the systemdescribed herein, including wired (cable/plug) and wireless methods.

One or more communication ports 238, also referred to as externalconnector(s), can be provided to allow communication with other devices,for example a PC communication (com) port can be provided to enablecommunication with systems that are separate from, or integral with, thesensor electronics module. The communication port, for example, maycomprise a serial (e.g., universal serial bus or “USB”) communicationport, allows for communicating with another computer system (e.g., PC,smart mobile phone, personal digital assistant or “PDA,” server, or thelike). In one exemplary embodiment, the sensor electronics module 12 isable to transmit historical data to a separate computing device forretrospective analysis by a patient and/or physician.

In conventional continuous analyte sensor systems, the on-skin portionof the sensor electronics is generally simplified to minimize complexityand/or size of on-skin electronics, for example, providing only raw,calibrated, and/or filtered data to a secondary display deviceconfigured to run calibration and other algorithms required fordisplaying the sensor data. In contrast, the sensor electronics module12 executes prospective algorithms used to generate transformed sensordata and/or displayable sensor information, including, for example,algorithms that: evaluate a clinical acceptability of reference and/orsensor data, evaluate calibration data for best calibration based oninclusion criteria, evaluate a quality of the calibration, compareestimated analyte values with time corresponding measured analytevalues, analyze a variation of estimated analyte values, evaluate astability of the sensor and/or sensor data, detect signal artifacts(noise), replace signal artifacts, determine a rate of change and/ortrend of the sensor data, perform dynamic and intelligent analyte valueestimation, perform diagnostics on the sensor and/or sensor data, setmodes of operation, evaluate the data for aberrancies, and/or the like,which are described in more detail in U.S. Pat. Nos. 7,310,544,6,931,327, U.S. Patent Publication No. US-2005-0043598-A1, U.S. PatentPublication No. US-2007-0032706-A1, U.S. Patent Publication No.US-2007-0016381-A1, U.S. Patent Publication No. US-2008-0033254-A1, U.S.Patent Publication No. US-2005-0203360-A1, U.S. Patent Publication No.US-2005-0154271-A1, U.S. Patent Publication No. US-2005-0192557-A1, U.S.Patent Publication No. US-2006-0222566-A1, U.S. Patent Publication No.US-2007-0203966-A1 and U.S. Patent Publication No. US-2007-0208245-A1,each of which is incorporated herein by reference in its entirety.Furthermore, the sensor electronics module 12 is configured to store thetransformed sensor data (e.g., values, trend information) and tocommunicate the displayable sensor information to a plurality ofdifferent display devices. In some embodiments, the display devices are“dummy” devices, namely, they are configured to display the displayablesensor information as received from the sensor electronics module 12,without any additional sensor data processing.

FIGS. 2B and 2C are perspective and side views of a sensor systemincluding a mounting unit 240 and sensor electronics module 12 attachedthereto in some embodiments, shown in its functional position, includinga mounting unit and a sensor electronics module matingly engagedtherein. In some preferred embodiments, the mounting unit 240, alsoreferred to as a housing or sensor pod, comprises a base 242 adapted forfastening to a host's skin. The base 242 can be formed from a variety ofhard or soft materials, and preferably comprises a low profile forminimizing protrusion of the device from the host during use. In someembodiments, the base 242 is formed at least partially from a flexiblematerial, which is believed to provide numerous advantages overconventional transcutaneous sensors, which, unfortunately, can sufferfrom motion-related artifacts associated with the host's movement whenthe host is using the device. The mounting unit 240 and/or sensorelectronics module 12 can be located over the sensor insertion site toprotect the site and/or provide a minimal footprint (utilization ofsurface area of the host's skin).

In some embodiments, a detachable connection between the mounting unit240 and sensor electronics module 12 is provided, which enables improvedmanufacturability, namely, the relatively inexpensive mounting unit 240can be disposed of when replacing the sensor system after its usablelife, while the relatively more expensive sensor electronics module 12can be reusable with multiple sensor systems. In some preferredembodiments, the sensor electronics module 12 is configured with signalprocessing (programming), for example, configured to filter, calibrateand/or other algorithms useful for calibration and/or display of sensorinformation. However, an integral (non-detachable) sensor electronicsmodule can be configured.

In some embodiments, the contacts 244 are mounted on or in a subassemblyhereinafter referred to as a contact subassembly 246 configured to fitwithin the base 242 of the mounting unit 240 and a hinge 248 that allowsthe contact subassembly 246 to pivot between a first position (forinsertion) and a second position (for use) relative to the mounting unit240. The term “hinge” as used herein is a broad term and is used in itsordinary sense, including, without limitation, to refer to any of avariety of pivoting, articulating, and/or hinging mechanisms, such as anadhesive hinge, a sliding joint, and the like; the term hinge does notnecessarily imply a fulcrum or fixed point about which the articulationoccurs. In some embodiments, the contacts 244 are formed from aconductive elastomeric material, such as a carbon black elastomer,through which the sensor 10 extends.

In certain embodiments, the mounting unit 240 is provided with anadhesive pad 250, disposed on the mounting unit's back surface andincluding a releasable backing layer. Thus, removing the backing layerand pressing the base portion 242 of the mounting unit 240 onto thehost's skin adheres the mounting unit to the host's skin. Additionallyor alternatively, an adhesive pad 240 can be placed over some or all ofthe sensor system 8 after sensor insertion is complete to ensureadhesion, and optionally to ensure an airtight seal or watertight sealaround the wound exit-site (or sensor insertion site) (not shown).Appropriate adhesive pads can be chosen and designed to stretch,elongate, conform to, and/or aerate the region (e.g., host's skin). Theembodiments described with reference to FIGS. 2B and 2C are described inmore detail with reference to U.S. Pat. No. 7,310,544, which isincorporated herein by reference in its entirety. Preferably,configurations and arrangements that provide water resistant,waterproof, and/or hermetically sealed properties are providedassociated with the mounting unit/sensor electronics module embodimentsdescribed herein.

Communication between Sensor System and Display Devices

FIG. 3 is an exemplary block diagram illustrating various elements ofsome embodiments of a continuous analyte sensor system 8 incommunication with display device(s) 14. The sensor system 8 may includea sensor 312 (also designated 10 in FIG. 1) coupled to a sensormeasurement circuit 310 for processing and managing sensor data. Thesensor measurement circuit 310 may be coupled to a processor 314 (alsodesignated 214 in FIG. 2A). In some embodiments, the processor 314 mayperform part or all of the functions of the sensor measurement circuit310 for obtaining and processing sensor measurement values from thesensor 312. The processor may be further coupled to a transceiver 316(e.g., part of item 12 in FIG. 1) for sending sensor data and receivingrequests and commands from an external device, such as the displaydevice 14, which is used to display or otherwise provide the sensor datato a user. The sensor system 8 may further include a memory 318 (alsodesignated 220 in FIG. 2A) and a real time clock 320 (part of item 12 inFIG. 1) for storing and tracking sensor data.

Wireless communication protocols may be used to transmit and receivedata between the sensor system 8 and the display device 14. The wirelessprotocol used may be designed for use in a wireless sensor network thatis optimized for periodic and small data transmissions (that may betransmitted at low rates if necessary) to and from multiple devices in aclose range (e.g., a personal area network (PAN)). For example, theprotocol may be optimized for periodic data transfers where transceiversmay be configured to transmit data for short intervals and then enterlow power modes for long intervals. The protocol may have low overheadrequirements both for normal data transmissions and for initiallysetting up communication channels (e.g., by reducing header overhead) toreduce power consumption. In some embodiments, burst broadcastingschemes (e.g., one way communication) may be used. This may eliminateoverhead required for acknowledgement signals and allow for periodictransmissions that consume little power.

The protocol may further be configured to establish communicationchannels with multiple devices while implementing interference avoidanceschemes. In some embodiments, the protocol may make use of adaptiveisochronous network topologies that define various time slots andfrequency bands for communication with several devices. The protocol maythus modify transmission windows and frequencies in response tointerference and to support communication with multiple devices.Accordingly, the wireless protocol may use time and frequency divisionmultiplexing (TDMA) based schemes. The wireless protocol may also employdirect sequence spread spectrum (DSSS) and frequency-hopping spreadspectrum schemes. Various network topologies may be used to support lowpower wireless communication such as peer-to-peer, start, tree, or meshnetwork topologies. The wireless protocol may operate in variousfrequency bands such as an open ISM band such as 2.4GHz. Furthermore, toreduce power usage, the wireless protocol may adaptively configure datarates according to power consumption.

The display device 14 may be used for alerting and providing sensorinformation to a user, and may include a processor 330 for processingand managing sensor data. The display device 14 may include a display332, a memory 334, and a real time clock 336 for displaying, storing andtracking sensor data respectively. The display device 14 may furtherinclude a transceiver 338 for receiving sensor data and for sendingrequests, instructions, and data to the sensor system 8. The transceiver338 may further employ a communication protocol.

In some embodiments, when a standardized communication protocol is used,commercially available transceiver circuits may be utilized thatincorporate processing circuitry to handle low level data communicationfunctions such as the management of data encoding, transmissionfrequencies, handshake protocols, and the like. In these embodiments,the processor 314, 330 does not need to manage these activities, butrather provides desired data values for transmission, and manages highlevel functions such as power up or down, set a rate at which messagesare transmitted, and the like. Instructions and data values forperforming these high level functions can be provided to the transceivercircuits via a data bus and transfer protocol established by themanufacturer of the transceiver circuit 316.

Components of the analyte sensor system 8 may require replacementperiodically. For example, the analyte sensor system 8 may include animplantable sensor 312 that may be attached to a sensor electronicsmodule that includes the sensor measurement circuit 310, the processor314, memory 318, and transceiver 316, and battery (not shown). Thesensor 312 may require periodic replacement (e.g., every 7-30 days). Thesensor electronics module may be configured to be powered and active formuch longer than the sensor 312 (e.g., for three, six or more months)until the battery needs replacement. Replacing these components may bedifficult and require the assistance of trained personnel. Reducing theneed to replace such components, particularly the battery, significantlyimproves the convenience of the analyte sensor system 8 to the user. Insome embodiments, the sensor session as defined above may correspond tothe life of the sensor 312 (e.g., 7-30 days). When a sensor electronicmodule is used for the first time (or reactivated once a battery hasbeen replaced in some cases), it may be connected to a sensor 312 and asensor session may be established. As will be further described below,there may be a process for initially establishing communication betweena display device 14 and the sensor electronics module when it is firstused or re-activated (e.g., the battery is replaced). Once the displaydevice 14 and sensor electronics module have established communication,the display device 14 and sensor electronics module may periodicallyand/or continuously be in communication over the life of several sensors312 until, for example, the battery needs to be replaced. Each time asensor 312 is replaced, a new sensor session may be established. The newsensor session may be initiated through a process completed using adisplay device 14 and the process may be triggered by notifications of anew sensor via the communication between the sensor electronics moduleand the display device 14 that may be persistent across sensor sessions.

The analyte sensor system 8 gathers analyte data from the sensor 312that it periodically sends to the display device 14. Data points aregathered and transmitted over the life of the sensor (e.g., 1, 3, 7, 10,15, 30 or more days). New measurements may need to be transmitted oftenenough to adequately monitor glucose levels. Rather than having thetransmission and receiving circuitry of each of the sensor system 8 anddisplay device 14 continuously communicating, the analyte sensor system8 and display device 14 may regularly and periodically establish acommunication channel between them. Thus, sensor system 8 cancommunicate via wireless transmission with display device 14 atpredetermined time intervals. The duration of the predetermined timeinterval can be selected to be long enough so that the sensor system 8does not consume too much power by transmitting data more frequentlythan needed, yet frequent enough to provide substantially real-timesensor information (e.g., measured glucose values) to the display device14 for output (e.g., display) to a user. While the predetermined timeinterval is every five minutes in some embodiments, it is appreciatedthat this time interval can be varied to be any desired length of time.These predetermined time intervals and associated communications arediscussed in more detail with respect to FIG. 9, below.

It should be appreciated that sensor system 8 performs a number oftasks, each of which consume a fair amount of power. Over the life ofsensor system 8, power consumption may serve as one of the biggestlimitations to completing more and more complex tasks, such as increaseddata transfer and updates to display device 14. Furthermore, should itbe desirable to further decrease the size of sensor system 8, the sizeof the battery may also need to be reduced, likely resulting in alsoreducing the life of sensor system 8. Consequently, systems and methodsfor achieving power savings in conjunction with sensor system 8 arehighly desirable.

Low Power Measurement Circuit and Sleep Current Detection

Some embodiments of sensor system 8 may utilize a low power measurementcircuit that is capable of switching between a measurement mode and alow power mode to conserve power usage. During the measurement mode,measurement circuitry can be powered and electrically coupled to sensorelectrodes to take sensor measurements. Also during the measurementmode, a charging circuit can be powered and electrically coupled to acapacitive circuit to charge the capacitive circuit. After a measurementis complete, the circuit can enter the low power mode. In the low powermode, the measurement circuitry can be decoupled from the sensorelectrodes and powered down, and the charging circuitry can be decoupledfrom the capacitive circuit and powered down. In addition, during thelow power mode, the capacitive circuit can be electrically coupled tothe sensor electrode or sensor electrodes to maintain a voltage acrossthe electrode(s). In this way, measurement circuitry can be powered downin between taking measurements to reduce power consumption, but yet avoltage can be maintained across the sensor electrodes through the useof capacitive circuit. Maintaining a voltage across the sensorelectrodes while measurement circuitry is powered down may be desired.Example low power measurement circuits are described in U.S. PatentPublication No. 2012007807 1, incorporated herein by reference in itsentirety.

In addition to using low power measurement circuitry, circuitry thatdetects any extra current flowing within sensor system 8 may be usefulin ensuring that system 8 is operating efficiently. For example,measuring any excess current flowing within the sensor system 8 when itis in a low power or sleep mode would be desirable. However, to have ameasurement means being actively powered to measure the excess currentwhile the system 8 is in sleep mode could be counterproductive,depending upon the implementation, as it could consume power to monitorpossible excess current. Furthermore, sending information related to theexcess current while the system 8 is in sleep mode may cause the system8 to wake up prematurely, which could also be undesirable.

Thus, a means for monitoring the current when sensor system 8 is instorage or sleep mode that does not need to be actively powered would bedesirable in some implementations. Additionally, a measurement means fordetecting excess current that does not cause the system 8 to prematurelywake up from sleep mode to receive the measurement information would bedesirable in some implementations. Such measurement means may beimplemented in, for example, a separate circuit for measuring currentwhen system 8 is in sleep mode (hereinafter referred to as “sleepcurrent”).

Reference is now made to FIG. 4A, which is a simplified block diagram ofan embodiment of a low power circuit 400 configured to detect sleepcurrent. Low power circuit 400 can include measurement circuitry 402,sensor electrodes 404 a and 404 b, and sleep current circuitry 408. Alsoillustrated in FIG. 4A is power supply circuitry 412 and controlcircuitry 414. Power supply circuitry 412 may be configured toselectively provide power to measurement circuitry 402. In someembodiments, power supply circuitry 412 will not be connected to sleepcurrent circuitry 408, as sleep current circuitry 408 may be configuredto operate independently and not require any extra power from circuit400. Control circuitry 414 may be configured to selectively enable powersupply circuitry 412 and selectively enable measurement circuitry 402.Power supply circuitry 412 can include any suitable power supply source,such as a rechargeable, replaceable or disposable battery. Power supplycircuitry 412 can also include any other circuitry needed to convert thepower source into a suitable voltage source to power the components ofcircuit 400. Control circuitry 414 can be implemented via an ASIC or ageneral purpose processor, for example.

Low power circuit 400 can power down measurement circuitry 402 from anactive measuring state to a low power inactive sleep state, where thesleep current is measured through the use of sleep current circuitry408. Control circuitry 414 can be configured to provide a sleep pulsesignal to sleep current circuitry 408 when in the inactive sleep state.In some embodiments, the sleep pulse signal is simply a pulse thatswitches the sleep current circuitry 408 into an on mode, and does notprovide any power for an ongoing period of time.

For example, control circuitry 414 may include a timer that places lowpower circuit 400 in sleep mode for 30 seconds. During this time, asleep pulse signal (e.g., as a single pulse) flows from controlcircuitry 414 to sleep current circuitry 408 to switch the sleep currentcircuitry 408 on. Sleep current circuitry 408 may charge a capacitor,where the voltage across the capacitor correlates with the sleep pulsesignal provided to sleep current circuitry 408. After the sleep mode hasterminated, an output voltage for the capacitor can be determined bysleep current circuitry 408. This output voltage may be correlated witha characteristic of the sleep pulse signal (e.g., amperes or totalcharge for the sleep pulse signal) to differentiate any charge in thecapacitor resulting from the sleep pulse signal from any sleep current.An error or fault can be identified if the output voltage is above orbelow pre-determined thresholds. For example, an error message can bedisplayed to a user if the output voltage is above or belowpre-determined thresholds.

FIG. 4B shows an example of sleep mode circuitry 408 for monitoringcurrent flowing within sensor system 8 when sensor system 8 is in areduced power or sleep mode. In some embodiments, sleep mode circuitry408 captures any current resulting from the sleep pulse signal as wellas any sleep current as a charge on a capacitor from a large currentsense resistor that may be automatically switched out of the circuit byhardware (e.g., internal to a processor) when the system 8 wakes orpowers up. The system 8 can then immediately read the charge on thecapacitor to determine if the total current reading (e.g., currentattributable to sleep pulse signal and the sleep current) is within anacceptable range.

Still referring to FIG. 4B, sleep current circuit 408 may include ananalog switch Ul powered by a battery BT1. A first resistor R1 maymaintain switch Ul in state S2, connecting battery BT1 to system groundGND. It should be appreciated that, in some embodiments, the sleep pulsesignal may simply change the state of sleep current circuit 408 into anactive measuring or on mode. The sleep pulse signal may comprise asingle pulse, being almost instantaneous and having no lasting duration(e.g., a millisecond or more). Generally, the sleep pulse signal mayresult in some charge in circuit 408. This resultant charge may besubtracted from the total measured charge to determine the sleep currentor taken into account when comparing the total charge to a threshold.

FIG. 4C shows a sleep timing diagram 450 with a sleep interval set for30 seconds. In some embodiments, software may be used to set up a timerthat will wake the processor from its sleep mode. The processor isbriefly active when entering sleep mode to set the timer (shown in thetime series “CPU Active” in FIG. 4C). In some embodiments, a sleep pulsesignal is generated (e.g., from a processor) that goes low for a shorttime (e.g., about 100 ms) before wake up occurs, switching battery BT1to state Si. The sleep pulse signal is shown in the time series“SLEEP_PLS_L” in FIG. 4C. The processor becomes active again at the endof the 30-second sleep interval.

Referring again to FIG. 4B, at state S1, capacitor C1 has a voltage thatcorrelates to the sleep pulse signal (due to resistor R2). This voltagemay be transferred through resistor R2 to capacitor C1. It will beappreciated that the sleep pulse signal is applied long enough to chargecapacitor C1 to the level of resistor R2.

When wake up of system 8 occurs, state S2 is re-entered, whilepreserving the voltage at capacitor C1. In some embodiments, softwaremay use an ADC channel (shown in FIG. 4B as ADC IN) to read the chargeon capacitor C1 before it is discharged through resistors R2 and R3. Thecharge at capacitor C1 due to the current received from battery BT1 viaresistor R1 may be accounted for when correlating the sleep pulse signalwith the charge on capacitor Cl (e.g., an amount of charge subtracteddue to current from battery BT1).

Because sensor system 8 may spend a substantial amount of time sleepingor in a lower power mode, if the output voltage on the capacitor ishigher than expected (e.g., greater than an amount expected from thesleep pulse signal, the internal battery of the sleep current circuit,or combination thereof), battery life may be significantly shortened dueto unwanted sleep currents in the system. This present circuit allowssensor system 8 to verify correct operation and normal battery drainwhen it is sleep mode. If a fault is indicated, diagnostics or remedialaction can occur. For example, in some implementations, the sensorsystem may monitor and record possible technical issues associated withthe sensor system 8. The technical issues may be recorder in a technicalsupport log file stored in memory of the sensor system

Auto-Zero Compensation

In some embodiments, an additional verification may be performed on asensor signal due to possible leakage currents. As used herein, leakagecurrent refers to any current that flows when the ideal current is zeroand the system 8 is an active measurement mode (e.g., as opposed tostandby, disabled, or “sleep” mode, as described above). These devicescan draw one or two microamperes while in their quiescent state comparedto hundreds or thousands of milliamperes while in full operation. Theseleakage currents are becoming a significant factor to portable devicemanufacturers because of their undesirable effect on e.g., battery runtime.

As is known by one of skill in the art, sensor data may comprise digitaldata in “counts” converted by an A/D converter from an analog signal(e.g., voltage or amps). Leakage current may affect the sensor datareading directly by showing an increase in counts (e.g., a high leakagecurrent will produce an increased value for the converted counts).

In some embodiments, the leakage current may change as a result of theinternal temperature of various hardware components (such as illustratedin FIG. 2A) changing. In such embodiments, the leakage current may bedetermined by: (1) determining if the internal temperature of one ormore hardware components has changed, and (2) if the internaltemperature of one or more hardware components has changed, measuringthe leakage current. For example, in some embodiments, the leakagecurrent may be measured by creating an open circuit at or near thelocation where leakage is expected. It should be appreciated that anycircuit capable of detecting leakage current, as is known by one ofskill in the art, may be implemented by the present disclosure.

In some embodiments, a leakage current is detected for sensor system 8using a leak detection circuit in communication with the sensor system8. The leakage current may be received by the sensor system (e.g., via aprocessor). Thereafter, an adjustment may be performed on or more sensorsignals using the leakage current. For example, the adjustment to thesensor signal may be subtracting the leakage current from a sensorsignal. In other words, the leakage current may be “auto-zeroed” outfrom the sensor signal. In some embodiments, the adjusted sensor signalmay be provided to a user in a desirable format (e.g. as sensor countdata).

Low Power Storage Mode

Some embodiments reduce the amount of power consumed by sensorelectronics module 12 by putting sensor electronics module in a powersaving storage mode while it is in storage. In general, a storage modecan be activated with a command at manufacturing that initiates aroutine implemented by software stored in memory, for example, to poweroff select circuitry in sensor electronics module 12 and put processormodule 414 into a low power mode (e.g., sleep mode). Sensor electronicsmodule 12 can then be placed in a package that places sensor electronicsmodule 12 next to a storage magnet, which keeps it in storage mode untilsensor electronics module 12 is pulled away from the magnet by a user.The storage magnet can be incorporated into the packaging directly nextto where the sensor electronics module 12 is held, for example.

In some embodiments, pulling a magnet away from sensor electronicsmodule switches sensor electronics module 12 out of a storage mode andinto a normal operation mode. For example, pulling the sensorelectronics module 12 away from the magnet can trigger an interruptline, which initiates an interrupt routine performed by software storedin the electronics module 12. Once started, the interrupt routine caninitiate a state machine implemented using sleep timer interrupts whichcheck periodically across multiple intervals, for a predetermined amountof time, such as five minutes, to validate that the sensor electronicsmodule 12 has indeed been moved away from the magnet. Once the statemachine concludes that the storage magnet has been removed, the statemachine puts sensor electronics module 12 in normal operation mode by,for example, pulling processor 314 out of low power mode, and restoringor providing power to other circuitry of sensor electronic module 12.

FIG. 5A is a simplified block diagram of an embodiment of sensorelectronics module 12 with a low power storage mode feature. For ease ofexplanation, FIG. 5A only illustrates select components of a sensorelectronics module 12 and it is understood that further components canbe incorporated into sensor electronics module 12, such as anycomponents discussed above with reference to FIG. 5A. Furthermore, asensor kit can also be provided that includes one or more sensorelectronics modules 12 and a plurality of sensors 10, which include lowpower mode storage feature(s). Such sensor kits are described in furtherdetail in U.S. Patent Publication No. 20120078071, incorporated hereinby reference in its entirety.

As illustrated in the embodiment of FIG. 5A, sensor electronics module12 includes a switch 520 configured to switch between a first state(e.g., closed state) when a force is applied to the switch and secondstate (e.g., open state) when the force is removed or sufficientlydiminished. In some embodiments, the applied force is a magnetic field,generated by any suitable means (e.g., mechanical or electrical). Switch520 is operatively connected to system processor 514, which is in turnoperatively connected to ASIC 524 via FET switch 522. Telemetry module532 is also operatively connected to microprocessor 514.

In some embodiments, switch 520 is a reed switch. In other embodiments,switch 520 is a Hall-effect switch. When switch 520 is a reed switch, itincludes one or more pairs of magnetizable, flexible, metal reeds whoseend portions are separated by a small gap when the switch is open. Thereeds may be hermetically sealed in opposite ends of a tubular glassenvelope. A magnetic field (from an electromagnet or a permanent magnet)will cause the reeds to come together, thus completing an electricalcircuit. Good electrical contact may be assured by plating a thin layerof non-ferrous precious metal such as low-resistivity silver over flatcontact portions of the reeds.

When switch 520 is a Hall-effect switch, it includes a transducer thatvaries its output voltage in response to a magnetic field. For example,in some embodiments, the Hall-effect switch is mounted onto a PCB,similar to other components of FIG. 5A. Hall-effect switch may betriggered by an external magnet, such as magnet 526 described below. Insome embodiments, a Hall-effect switch may be preferable to other switchtypes such as a reed switch, which may be sensitive to vibration andshock and to a light switch, since not optical window is required forthe Hall-effect switch.

In some embodiments, the sensor electronics module 12 includes alight-sensitive sensor that triggers the switch between the first stateand the second state. That is, the light sensitive-sensor takes thesensor electronics module out of a storage mode when the light-sensitivesensor is exposed to light in accordance with some embodiments. Toillustrate, sensor electronics module 12 can be placed in a low power,storage mode during manufacture, shipment and storage so the sensorelectronics module consumes little power. A light-sensitive sensor canbe included in sensor electronics module 12 that is shielded from lightby a protective cover and the sensor electronics module placed in astorage mode in a similar manner as described above. Thus, duringmanufacture, shipment and storage of sensor electronics module 12, thesensor electronics module can be in the storage mode.

A user can remove the protective cover—thereby exposing thelight-sensitive sensor to light—to cause the sensor electronics moduleto switch from the storage mode to a higher power, operational mode(e.g., when the sensor electronics module 12 needs to be woken up foruse).

An exemplary process 550 for placing sensor electronics module 12 into astorage mode and taking sensor electronics module out of the storagemode will now be described with reference to the flowchart depicted inFIG. 5B. It is understood that process 550 is illustrative only, andthat additional steps can be added and/or one or more steps of process550 can be removed. In addition, the steps of process 550 are notlimited to the described order.

Process 550 starts with activating a storage mode at block 552. Avariety of methods can be used to activate the storage mode. In someembodiments, a storage mode command is transmitted from an externaltelemetry device and received by sensor electronics module 12 viatelemetry module 532. The telemetry module 532 relays the storage modecommand to microprocessor 514, which, in response, initiates a storagemode routine. In some embodiments, a storage mode command can beinitiated by inputting a command via a user interface, such as userinterface 222 of FIG. 2, of a sensor electronics module 12.

Further to block 552, the storage mode routine can include turning offelectronic components of sensor electronics module 12 and/or placingelectronic components of sensor electronics module 12 in a low powermode (also referred to as a sleep mode). In some embodiments,microprocessor 514 is placed in a low power mode and all otherelectronic components that need not be used during storage of the sensorelectronics module 12, such as a potentiostat 210, and any unneededcircuits are turned off. For example, processor 514 of FIG. 5A can senda switch enable signal via a data line to turn off FET switch 522,which, in turn, turns off ASIC 524.

Also included in block 552, magnet 526 is placed in proximity to switch520 to cause switch 520 to be in a first state (e.g., a closed state).In some embodiments, switch 520 needs to be in the first state prior tosensor electronics module 12 receiving the storage mode command in orderfor the storage mode routine to be initiated. In another embodiment, thestorage mode interrupt routine is initiated as long as switch 520 isplaced in the first state during a predetermined amount of time afterthe sensor electronics module 12 receives the storage mode command.

In some embodiments, the sensor electronics module 12 is checked to makesure it entered storage mode after the transmitting the storage modecommand. This can be accomplished by placing the sensor electronicsmodule 12 in a radio transmission detection device that monitors radiofrequencies being emitted from the sensor electronics module. Becausethe sensor electronics module 12 automatically sends periodic radiofrequency transmissions (e.g. every five minutes) in some embodiments,as discussed above, the radio transmission detection device will detectradio transmission from the sensor electronics module should the sensorelectronics module not be placed in the storage mode and should theradio transmission detection device be monitoring the sensor electronicsmodule for a time period longer than the periodic transmission timeinterval. By performing this check, the manufacturer can reduce thelikelihood that a sensor electronics module 12 is sent to a customerwith a depleted battery due to the sensor electronics module not beingplaced in the storage mode.

Next, at block 554, microprocessor 514, while in a low power mode,monitors for an interrupt signal from switch 526. In some embodiments,an interrupt signal is sent from switch 526 when switched to a secondstate (e.g., open state), which occurs when magnet 526 is no longer insufficient proximity to switch 520 to keep switch in the first state.This can occur, for example, when sensor electronics module 12 isremoved from storage packaging in which magnet 526 can be embedded.

At decision block 556, process 550 determines whether an interruptsignal has been received. If not, then process 550 returns to block 554to continue monitoring for an interrupt signal. If it is determined thatan interrupt signal has been received, then process 550 proceeds toblock 558.

Process 550 may initiate a state machine validation routine at block558. In some embodiments, the state machine validation routine verifiesat predetermined intervals that the switch signal continues for apredetermined amount of time. For example, each predetermined intervalcan be one minute and the predetermined amount of time can be fiveminutes. In such an example, processor 514 can be woken each interval(e.g., each minute) to verify that the switch signal continues to be inthe inactive state and the processor is placed in a sleep mode inbetween verification intervals to conserve power. Should microprocessor514 determine that the switch signal has returned to the activatedstate—which can occur if magnet 526 is moved to be in sufficientproximity to switch 520 or if a signal glitch occurs, (which can befurther mitigated using a debounce or second check to make sure thesignal was not glitched), for example—then the validation routine endsand it is determined that the removed magnet state is not valid. In someembodiments, a signal glitch may be the result of stray magnetic fields.However, the removed magnet state is considered valid if, after theexpiration of the predetermined amount of time, microprocessor 514 hasseen the correct switch signal level at each verification interval.

Next, decision block 560 queries whether the removed magnet state isvalid. If not valid, then process returns to block 554. However, ifvalid, then process proceeds to block 562.

At block 562, process 550 deactivates the storage mode. Here, componentsof sensor electronics module 12 are switched into a normal operationmode. For example, microprocessor can be woken out of a sleep mode andturn on FET switch 522, which, in turn, enables ASIC 524 and any othercomponents of sensor electronics module 12 that are used during a normaloperation mode.

In some embodiments, process 550 can be performed not only when thesensor electronics module 12 is placed in storage, but also after sensorelectronics module 12 is initially removed from its packaging. In thisway, a user can place the sensor electronics module in a low power modewhenever desired; for example, when on an airplane or any other time itis determined that the sensor electronics module 12 should not or neednot be powered. In this regard, some embodiments provide a magnetic clip(not shown) that is configured to hold magnet 526 in proximity to switch520. A user can then attach the magnetic clip to sensor electronicsmodule 12 and initiate a storage mode command to begin process 550.

In some embodiments, sensor electronics module 12 can be configured toprevent re-entry of the storage mode once taken out of the storage mode.This may be beneficial to prevent the sensor electronics module 12 fromaccidentally re-entering storage mode during use, among other reasons.Sensor electronics module 12 can be configured to prevent storage modeafter the sensor electronics module 12 is taken out of storage mode bydisabling switch 420 or the data line connecting switch 520 to processor514, for example.

In some embodiments, a process is used to prevent or reduce thelikelihood of inadvertent reentry into storage mode. For example, in oneimplementation, a simple transition on the switch 520 is not sufficientto put the transceiver 316 (e.g., of sensor electronics module 12) backin storage mode. In some embodiments, a specific complex magnetic pulsewaveform is required in order to put the sensor electronics module 12into a test mode in which the sensor electronics module is configured tobe able to receive a storage mode command over an RF interface. Inaddition, the storage mode command can be unique for each sensorelectronics module 12 and can be required to be received within apredetermined amount of time (e.g., 10 seconds) of the sensorelectronics module 12 successfully entering the test mode. If any ofthese conditions are not met, the sensor electronics module 12 does notreturn to storage mode.

Automatically Switching on Sensor Electronics

With reference to FIG. 1, some embodiments of a system for continuousmeasurement of an analyte automatically switch a sensor electronicsmodule 12 from a low power mode (e.g., power off mode or low powerstorage mode) to a higher power operational mode when the sensorelectronics module is attached to a disposable sensor, such ascontinuous analyte sensor 10 and/or mounting unit 240. Doing so canreduce power consumption during the shelf-life of the sensor electronicsmodule 12 as well as in between sensor attachments. As described abovewith respect to FIG. 2B and 2C, some embodiments of sensor system 8 canuse sensor electronics module 12 that is configured to be releasablyattached to mounting unit 240, wherein the mounting unit holds sensor 10when the sensor is implanted in a host.

In some embodiments, a connector pad of sensor electronics module 12,configured to contact corresponding contact(s) of mounting unit 240, canbe split into two individual, electrically insulated connectors. Thecontact(s) of the mounting unit 240 can be in the form of a conductive,flexible “puck”, designed to make contact with the corresponding “split”connector of the sensor electronics module when sensor electronicsmodule is attached to the mounting unit. Once in contact, the splitconnector and the conductive puck result in a short circuit. This cancause sensor electronics module to switch on after an impedancemeasurement or switch on a battery voltage to wake up the sensorelectronics module.

FIGS. 6 and 7 are top views of respective embodiments of splitconnectors 600, 700 of sensor electronics module 12. FIG. 6 illustratesan embodiment of a split connector 600 having an axial symmetric layout,where connector 600 is split into two semicircular partial contacts 602a and 602 b. FIG. 7 is an embodiment of a split connector 700 having aconcentric (co-axial) design, where a first partial contact 702 a isencircled by a second partial contact 702 b. A space is provided betweencontacts 702 a and 702 b to insulate the contacts from one another.

FIG. 8 illustrates a partial cross-sectional view of a sensorelectronics module attached to a mounting unit in accordance with someembodiments. Here, sensor electronics module 12 is attached to mountingbase 840, which can include any of the features of mounting base 240described herein. When attached, both partial contacts 802 a and 802 bof sensor electronics module 12 make contact with conductive sensor puck804 of mounting unit 840. Partial contacts 802 a and 802 b can bepartial contacts 802 a and 802 b, respectively, or partial contacts 702a and 702 b, respectively, discussed above. The contact allows forswitching on sensor electronics module 12 as well as providingconnection of a potentiostat (not shown in FIG. 8) in the sensorelectronics module with sensor 810.

The embodiment of FIG. 8 uses electronic switch 806 based on ameasurement of impedance (resistance) between contacts 802 a and 802 b.Without sensor puck 804 in contact with partial contacts 802 a and 802b, the impedance measurement should be, theoretically, infinitely high.When sensor electronics module 12 is attached to sensor unit 820,conductive puck 804 shorts the two contacts 802 a and 802 b, whichresults in a measurable, low resistance. This resistance can be measuredby a simple circuit incorporated in switch 806. The circuit can drawminimum or no power. Upon measuring the low resistance, switch 806 canswitch power up the electronics module 12 from a low power state.

The switch 806 can connect and disconnect a battery circuit to causesensor electronics module 12 to switch between a low power state and ahigh power state. The battery circuit can be separate from orincorporated in the sensor electronics module 12. Further, whenconnected, the battery circuit can power some or all the components ofthe sensor electronics module in some embodiments. For example, in someembodiments a first battery circuit connected to the switch 806 providespower to some, but not all, components of the sensor electronics module,such as components used to drive the sensor during a measurement cycle,when connected, and a separate, second battery circuit provides power tocomponents of the sensor electronics module regardless of whether thefirst battery circuit is connected via the switch. The first and secondbattery circuits can be powered by the same or different batteries.

When switch 806 is connected to a battery circuit, connection of themounting base 840 to sensor electronics module 12 causes switch 806 toclose the battery circuit, which powers up the sensor electronicsmodule. Further, disconnecting the sensor unit 820 from the sensorelectronics module 12 causes switch to open the battery circuit, whichpowers down the sensor electronics module.

In addition to or instead of one or more connector pads of sensorelectronics module 12, an electrode probe that determines if sensorelectronic module 12 is connected to a sensor 10. For example, in someembodiments, an electrode probe e.g., part of or in communication with asensor electronic module 12, may send a signal e.g., every five minutesto determine if sensor electronic module 12 is connected to sensor 10.In some embodiments the probe conducts periodic checking for theconnection between the sensor electronics module 12 and sensor 10. Theprobe signal may be selected from electrical (e.g. resistance),mechanical, etc. signals.

Sensor Initialization and Communication

Once sensor electronics module 12 has been switched from a low powermode (e.g., power off mode or low power storage mode) to a higher poweroperational mode (e.g., when the sensor electronics module 12 is firstattached to a disposable sensor 10), a sensor initialization processbegins in accordance with some embodiments. Accordingly, each time a newsensor 10 is connected to the sensor electronics module 10, aninitialization process may occur in accordance with some embodiments.

For example, when a sensor is first inserted into a host, there is atime when the sensor may need to equilibrate or stabilize (e.g., thesensor may hydrate or swell, tissue damage and an immune response mayresult from insertion of the sensor, etc.), as is known to those ofskill in the art. Furthermore, during this equilibration time period,the sensor may not provide accurate measurements because the biasvoltage when first applied needs to come up to a stable value.Consequently, in some situations it can be desirable to wait an amountof time after insertion of the sensor to allow the sensor to equilibratein vivo. In some embodiments, the sensor electronics can perform aninitialization process aid in stabilizing the sensor. A non-limitingexample includes applying a voltage that is higher than the normal biasvoltage to the sensor.

Use of Data Communication Protocols

FIG. 9A is a flow diagram of an exemplary communication between ananalyte sensor system 8 and a display device 14 for communicatingglucose measurement values. The data transfer may happen periodically,at times separated by an update interval T_(update) that may correspondto a period of obtaining and sending a recently measured glucose value(e.g., five minutes). In between these data transfer procedures, thetransceiver 316 of the analyte sensor system 8 can be powered down or ina sleep mode to conserve battery life. As such, the analyte sensorsystem 8 may therefore establish a communication channel with thedisplay device 14 once per update interval T_(update). Establishing acommunication channel may occur during a transmission window T_(window),within an update interval T_(update).

To establish a communication channel, the analyte sensor system 8 maysend one or more message beacons during of a transmission windowT_(window) within an update interval T_(update). Each message beacon maybe considered an invitation for a display device 14 to establish acommunication channel with the sensor system 8. A beacon may includedata including a challenge value for authenticating a display device 14.During initial system set up, the display device 14 may listencontinuously until such a message beacon is received. When the beacon issuccessfully received, the display device 14 can acknowledge thereception to establish communication between the devices. In response tothe beacon, the display device 14 may send a message requesting ameasurement along with a computed value for authentication. Onceauthenticated, the analyte sensor system 8 and display device 14 mayexchange information to determine how data will be exchanged (e.g., aspecific frequency, time slot assignment, etc.). When the desired datacommunication is complete, the channel can be closed, and thetransceiver 316 of the analyte sensor system 8 (and possibly thetransceiver 338 of the display device 14 as well) can be powered down.The entire data transmission window interval T_(window), for providingdata to one or more display devices 14 may be a small fraction of theupdate interval T_(update). For example, T_(update) may be five minutesand the data transmission window interval T_(window) may be thirtyseconds. As such, the transceiver 316 of the analyte sensor system 8 mayonly be powered for substantially 30 seconds of a five minute T_(update)interval. This may significantly reduce power consumption. In somecases, the transceiver 316 is not completely powered down, but enters alow-power mode when not transmitting. After a T_(update) interval haselapsed, the transceivers 316, 338 can be synchronized to power up againsubstantially simultaneously, and establish a new communication channelusing the same process to exchange any new data as shown in FIG. 9A.This process may continue, with new communication channels beingestablished at the pre-determined intervals.

To allow for some loss of synchronization between the two devices inbetween transmissions, the analyte sensor system 8 may be configured tosend a series of message beacons 902 in a window of time around thescheduled transmission time (e.g., 8 message beacons per second for 4seconds). Any one of the message beacons can be used to initiate theestablishment of a new communication channel when it is received by thedisplay device 14. After communicating with one device during thetransmission window, the analyte sensor system 8 may send out furthermessage bacons 904. These beacons can be received and used to establishother communication channels with other devices (e.g., other displaydevices) during the transmission window T_(window). However, in someembodiments, if it is known that the analyte sensor system 8 is onlycommunicating with a single display device, then the transmission windowT_(window) can be terminated at the same time as closing thecommunication channel with the display device.

FIG. 9B is a timing diagram of an exemplary sequence for establishing acommunication channel between an analyte sensor system 8 and a displaydevice 14. The display device 14 may initially “wake up” its transceiver316 and wait to receive a beacon from the analyte sensor system 8. Oncethe analyte sensor system 8 begins sending beacons, it may take one,two, or more beacons for the display device 14 to receive the beacon andrespond with a request. Once the beacon is received and the requestsent, data may thereafter be sent and/or received as shown by the shadedtime slots. The channel can then be closed once analyte sensor system 8and display device 14 determines that all requested data has beentransmitted to the respective devices or it the transmission window timeexpires. At the start of a new T_(update) interval, the process isrepeated.

Continuously re-establishing a new communication channel to allow forpartially or wholly powering down the transceiver 316 during each updateinterval T_(update) can provide significant power savings and can allowthe sensor electronics module 12 to operate continuously for six monthsor more without requiring a battery replacement. Furthermore, ratherthan blindly transmitting glucose data points during the transmissionwindow T_(window), communication channels may be established so thatonly the desired display devices 14 may receive the glucose information.This may prevent unauthorized use and interception of glucosemeasurement values. In addition, by establishing a secure two-waycommunication channel, requests for specific glucose measurement valuesor communication of calibration or configuration information may betransmitted on an as-needed/requested basis between the sensor system 8and display device 14.

Also, in some embodiments, the communication window need not open duringevery update interval T_(update). Instead, the window can open everysecond, third or fourth update interval T_(update), for example, so thatcommunication between the sensor system 8 with the display device 14occurs less frequently than every update interval T_(update). Doing socan further reduce power consumption. Accordingly, a window frequencyvariable F_(window) can be used that dictates a frequency the windowopens.

In some embodiments, the update interval T_(update), transmission windowT_(window) and/or window frequency F_(window) may be variable.T_(update), T_(window) and/or F_(window) can be user configurable (e.g.,by inputting a value for the variable using user interface of displaydevice 14) and/or automatically varied by the sensor system 8 or displaydevice 14 based on one or more criteria. The criteria can include: (i) amonitored battery power of the sensor system 8, (ii) a currentlymeasured, previously measured and/or predicted glucose concentrationsmeeting or exceeding a predetermined threshold, (iii) a glucoseconcentration trend of the host based on currently measured, previouslymeasured and/or predicted glucose concentrations, (iv) a rate of changeof glucose concentration of the host based currently measured,previously measured and/or predicted glucose concentrations meeting orexceeding a predetermined threshold, (v) whether the host is determinedto be in or near hyperglycemia based on currently measured, previouslymeasured and/or predicted glucose concentrations, (vi) whether the hostis determined to be in or near hypoglycemia based on currently measured,previously measured and/or predicted glucose concentrations, (vii) userinputted activity of the host (e.g., exercising or sleeping), (viii)time since a sensor session has started (e.g., when a new sensor 10 isused), (ix) one or more errors detected by sensor system 8 or displaydevice 14, 16, 18, 20, and (x) type of display device.

T_(update), T_(window) and/or F _(window) and other configuration itemsdescribed herein may form part of a communication protocol profile thatmay be stored on any device that implements the fundamentalcommunication protocol to allow for a customized use of the protocol forreceiving glucose measurement values, such as sensor system 10 anddisplay device 14.

FIG. 10 is a flowchart of an exemplary method for sending glucosemeasurement values from an analyte sensor system 8 to a display device14. At a pre-determined time in an update interval T_(update), ananalyte sensor system 8 may activate a transceiver 316 as shown in block1002. This may include powering the transceiver 316 or awakening thetransceiver 316 from a low power mode/state such as a sleep mode. Inblock 1004, the transceiver 316 may open and establish an authenticatedtwo-way communication channel between the analyte sensor system 8 and adisplay device 14. If the channel is established, in block 1006, theanalyte sensor system 8 and the display device 14 may transmitinformation between them, either automatically (e.g., device determinesa triggering event to transmit specific information) or in response to arequest received from the other device. Such information can include oneor more glucose measurement values, calibration information, alertsettings, communication synchronization information, and the like. Oncethe transmission is complete and data requested by the display device 14and sensor system 10 is sent, the analyte sensor system 8 may close thecommunication channel. In block 1010, the analyte sensor system 8 maydeactivate the transceiver 316 such as powering-down the transceiver orcausing it to go into a low power mode. The operations in block 1004through 1008 may be repeated with additional display devices until thetransmission window T_(window) closes. The analyte sensor system 8 maythen wait for the next transmission window T_(window) to open as shownin block 1012, and in the meantime gather glucose measurement values,before the process is repeated continuously over the duration of asensor session (e.g., corresponding to the life of non-durable sensor).Between each transmission window T_(window), a new analyte sensormeasurement may be obtained and stored for transmission.

User-Initiated Switching on Sensor Electronics via NFC

As described above, in some embodiments, sensor electronics module 12may be automatically switched from a low power mode (e.g., power offmode or low power storage mode) to a higher power operational mode whenthe sensor electronics module is attached to a disposable sensor. In atleast some of these embodiments, the initialization or run-in processmay take time to ensure that the sensor is stable before allowing thesensor to make and/or transmit measurements.

In other embodiments, the user may switch the mode of the transceiver316 from a low power mode to a higher operational power mode. Forexample, in some embodiments, it may be advantageous to allow the userto wake the analyte sensor system 8 from its storage mode.

In some embodiments, analyte sensor system 8 further includes near fieldcommunication (NFC) capability. In some embodiments, an NFC tag isintegral to the electronics in sensor system 8 (shown as NFC tag 322 inFIG. 3) or embedded in e.g., the housing or mounting unit 240. While notshown explicitly, NFC tag 322 may be included as part of transceiver316, making transceiver 316 a “smart transceiver”.

As can be appreciated, NFC is a set of short-range wirelesstechnologies, typically requiring a distance of 10 cm or less.Currently, NFC operates at 13.56 MHz on ISO/IEC 18000-3 air interfaceand at rates ranging from about 106 kbit/s to 424 kbit/s. NFC generallyincludes an initiator and a target, where the initiator activelygenerates a radio frequency (RF) field that can power a passive target.

In some embodiments, analyte sensor system 8 corresponds to the NFCtarget and a display device 14 such as a mobile phone (e.g., smartphone)capable of NFC communication corresponds to the NFC initiator. In suchembodiments, the smartphone may include a software application or “app”that can be used for communication with analyte sensor system 8. In someembodiments, the smartphone app may be configured to prompt the user toenter information specific to sensor system 8 (e.g., transmitter serialnumber) to wake the electronics module 12 out of storage mode.Thereafter, the smartphone app may activate the NFC functionality andinstruct the user to hold the smartphone in close proximity (e.g.,within 1 ft.) to the sensor system 8.

In some embodiments, the smartphone provides energy to NFC tag 322 bygenerating an RF field. The smartphone may also transmit e.g.,identification information, and a command for the electronics module 12to wake out of storage mode. It should be appreciated that theidentification information may be specific to the sensor system 8 andserve as a validation that the NFC process is authenticated. In somealternate embodiments, the smartphone may read the e.g., transmitterserial number from the NFC tag 322, automatically enter it into theapplication, and proceed with the wake up process.

Once NFC tag 322 has received the correct wake up command, it can send asignal to an interrupt input on processor 314. After processor 314 hasreceived the interrupt, the processor 314 may exit the low-power sleepmode and begin the normal operation of the sensor system 8, withinminimal delay.

Because of the short communication range, NFC activation may inherentlyprovide good security for activating the sensor system 8. Additionally,the use of a specific unique transmitter ID and a wake command addfurther security to the activation process.

In some embodiments, reading the transmitter ID from NFC tag 322 may beused for pairing electronics module 12 that is already awake to areceiving device such as a laptop or another smartphone. Such a pairingprocess is described below.

Pairing of Two or More Devices

In some embodiments, pairing of two devices (e.g., a master and slavedevice) may be required to establish a relationship between two devicesthat want to communicate with one another. Pairing may be accomplishedduring the channel establishment process described above between the twodevices. Establishing a channel may involve broadcasting a unique ID byone device and a search and acquisition of this ID by another device.

A parameter that may be used in device pairing is the master device ID.In order to establish a communication channel, a master transmitter maybroadcast its device ID (along with some other information) in the abovedescribed beacon and the receiver checks for the presence of the deviceID of the transmitter with which it wants to communicate in the receivedbeacons. The device ID may be a 2-byte value representing a specificmaster device, for example.

Although a master device ID may provide some level of security, in thata slave device can be programmed to communicate only with a masterdevice having a particular device ID number, additional security can beuseful in some embodiments. As described above, to save power bydeactivating the transceiver 316 of the analyte sensor system 8, acommunication channel may be re-established during each update intervalT_(update). As such, as part of the channel establishment process,regular and repeated re-authentication may also be provided.

To provide additional security, some embodiments of the presentinvention can use two pieces of information to pair a receiver with aparticular transceiver device. These two pieces of information includethe device ID described above and another value which is referred toherein as a sensor security code. The device ID is used as describedabove to e.g., filter receipt of non-matching messages at the lowestlayer of the protocol stack. The sensor security code is used for e.g.,a key based authentication scheme at the software application layer ofthe system. In some embodiments, both the device ID and the sensorsecurity code can be derived from an identifier (e.g., a manufacturer'sserial number) associated with the sensor system 8.

As seen in the embodiment of FIG. 1, the sensor system 8 comprises twofundamental components, the continuous sensor 10 and the electronicsmodule 12. These two components may be separable from one another,allowing, for example, replacement of the continuous sensor portion 10.In this case, the identifier may be etched into, printed on or otherwiseattached to a housing of the electronics module portion 12.

The sensor system 8 may include seven alphanumeric characters printed ona housing of the sensor system 8, which can comprise the identifier usedfor identification purposes. This alphanumeric series of characters maybe used to generate both the device ID used in the master beacons toestablish a channel and to generate the sensor security code used foradditional security in the glucose monitoring system.

NFC and Window Transitioning

As explained above, in some embodiments, it may be desirable to allowthe user to wake up or turn on electronics module 12. As presentedabove, the transceiver 316 may be off while in storage mode or inbetween transmission windows (e.g., where the transceiver 316communicates with another device 14 every 5 minutes).

NFC wake up can cause immediate or forced communication betweenelectronics module 12 and e.g., a smartphone or other device. Suchforced communication can occur as described above, such as when a useruses a smartphone application to wake up the electronics module 12. Itcan be appreciated that the forced wake up would often be out of syncwith the normal communication window (e.g., every 5 minutes). Thus, insome embodiments, the forced wake up can cause the transmission windowto start over at the time the forced communication commences. In otherembodiments, the forced wake up can cause a break or gap in thetransmission window, but does not cause the transmission window to startover. Further description on transmission window initialization andcommunication is provided below.

Several benefits may be realized from NFC forced wake up that is out ofsync with the normal transmission window. For example, such NFC wake upmay be used to cause information to be sent almost immediately (e.g., inreal-time), such as: transfer a calibration value to the sensor system 8(e.g., at transceiver 316) and get an updated estimated glucose value(EGV) back to the display device (e.g., at transceiver 338), send downnew settings (e.g., alarm settings, calibration settings, etc.) to thesensor system 8, pair a display device 14 to the sensor system 8. Insome embodiments, NFC wake up make also be used to enable test modes andcode upgrades.

As described above, the NFC forced wake up may allow the pairing ofelectronics module 12 of sensor system 8 with another display device 14such as a smartphone. This pairing may be done without requiring amechanical button, such as is necessary for e.g., Bluetooth pairing.

While immediate communication using NFC has generally been referred toas NFC wake up, it should be appreciated that if the communicatingdevices are already awake, that wake up is not necessarily performed.Rather, in such embodiments, the communication is a forced communicationthat sends some sort of immediate data, such as a calibration value. Forexample, in some embodiments, NFC may be used to start theinitialization period when a new sensor 10 is attached to sensor system8. This may allow initialization to begin immediately regardless ofwhere the transmission window is (e.g., when the next transmissionwindow will begin).

Transmission Pause Mode

In some embodiments, it may be desirable to allow a user to causeelectronics module 12 to enter a suspended or pause mode. Suchtransmission pause mode may be useful during times when a user may beprohibited from transmitting data, such as on an airplane. Such a modemay allow a user to not have to power down electronics module 12.Rather, the electronics module 12 is suspended from transmittinginformation for a predetermined duration of time.

In some embodiments, a user may initiate a “transmission pause mode”request in a software application on their display device 14 such as asmartphone when the user is in the airport or on an airplane. Thesmartphone may prompt the user to enter the estimated duration e.g., ofthe flight or time T. The smartphone may thereafter send a command tothe electronics module 12 to enter into the “transmission pause mode”for a certain time duration, e.g., time T.

Upon receiving the “airplane mode” command, electronics module 12 may beconfigured to decrease its RF transmission power for the duration oftime T. In some embodiments, after time T has elapsed, electronicsmodule 12 returns to its normal RF power level and resumes normaloperation.

A benefit of having an “transmission pause mode” is that electromagneticenergy produced by sensor system 8 may be minimized during a flight(e.g., minimizing any interference of airplane electronic systems due toradio transmissions from the sensor electronics module).

In some embodiments, “transmission pause mode” may be implemented usingNFC. In some embodiments, a user may wake electronics module 12 from the“transmission pause mode” using NFC/.

Adjustable Integration Window

The information communicated from the sensor system 8 to display device14 generally includes or relates to sensor data. In one example, thesensor data comprises digital data in “counts” converted by an A/Dconverter from an analog signal (e.g., voltage or amps) and includes oneor more data points representative of a glucose concentration. Sensordata may include a plurality of time spaced data points from a sensor,such as a from a substantially continuous glucose sensor, whichcomprises individual measurements taken at time intervals ranging fromfractions of a second up to, e.g., 1, 2, or 5 minutes or longer. Inanother example, the sensor data includes an integrated digital valuerepresentative of one or more data points averaged over a time period,or integration window.

As described elsewhere herein, for sensor calibration, a user may inputor enter a reference value at some point in time. For purposes ofillustration, the following explanation uses a blood glucose value (BGV)as the reference value, although it is understood that othermeasurements can be used as a reference value instead. In someembodiments, a calibration algorithm will then match or pair the BGVwith the last available integrated sensor signal or value to calibratethe data set. In some embodiments, a calibration algorithm will thenmatch or pair the BGV with an integrated sensor signal having a timestamp that is proximate to the time stamp of the BGV to calibrate thedata set. Accordingly, the time difference between the entered BGV andthe last available integrated sensor value could be the maximum timebetween the transmission windows (e.g., 5 minutes). In addition to thistime difference, the integrated sensor signal or value may be delayeditself due to processing lag time due to filtering and the like. Forexample, the integrated sensor signal may have a delay of 2.5 minutesbecause of data filtering, making a potential time delay about 7.5minutes. It can be appreciated that a time difference or delay can havea negative impact on system accuracy, as the physiological glucose levelmay have changed during that time, especially in the case of when thesystem is calibrated when the physiological glucose level is changingrapidly.

In some embodiments, to provide an improved match between the BGV andintegrated sensor signal, the integrated sensor signal may be provided“on demand” or in real-time (e.g., at the point in time when user entersa BGV for calibration). In some embodiments, the integrated sensorsignal may be provided using software (e.g., one or more algorithms)that records and/or manipulates sensor signal data.

For example, in some embodiments, the sensor signal may be captured andintegrated every 30 seconds. Every 5 minutes, ten of these 30 secondvalues are averaged to provide an integrated sensor signal to thealgorithm. The collected sensor signals and integrated values may bestored for example, in a memory buffer which may be part of e.g., memory318. It should be appreciated that the integration value parameters usedare exemplary only, and that any sampling duration and sampling numberis contemplated.

To provide an integrated sensor signal when a BGV is entered, theintegration window (and hence the values used for providing theintegrated sensor signal) may need to be shifted. This integrationwindow shifting or adjusting may be achieved by: (1) storing the lastten 30 second data points in a memory buffer; (2) when a new 30 seconddata point comes in, entering the new data point in the buffer anddeleting the oldest data point; and (3) when a calibration or BGV isentered, calculating the integrated sensor signal on the most recentdata point values stored in the buffer. In the present example, a 5minute averaged sensor signal can be provided that is matched within 30seconds of the entered calibration value, thereby yielding improvedaccuracy. In some embodiments, the accuracy of the averaged sensorsignal can be confirmed by comparing a time stamp associated with theintegration value to the time stamp associated with the enteredcalibration value.

While the example provides using ten 30 second values, any number ofsamples or data points for any duration of time that results in anintegration window of a fixed period may be used. However, having thevalues selected from integration window shifted to be closer to thecalibration value will generally be more representative of the BGV. Forexample, in some embodiments, the averaging of the integrated sensorsignal may be performed or centered around the entered glucose value(e.g., taking the five 30 second points before the BGV and the five 30second points after the BGV). Centering the integration sensor signalaround the BGV may result in minimizing any time delay present in theaveraged five minute value.

Also, in some embodiments, a weighted average that is more favorably orheavily weighted on the data point(s) in time closest to the entered BGVmay be used. In some embodiments, additional tools such as adaptivefiltering may be used to monitor the noise of the points.

In addition or instead of using data values stored in the memory buffer,the integrated sensor signal or value may be extrapolated using e.g., atleast one or more values stored in the memory buffer. In some examples,the integrated sensor signal may be extrapolated to a point of 2.5minutes in the future using five 30 second data values stored in thebuffer. In other embodiments, the integrated sensor signal may beextrapolated to a point of 2.5 minutes in the future using the rate ofchange on the previous sampled data points.

In some embodiments, to improve the accuracy of matching the enteredglucose values with the integrated sensor signals, a time stamp may beprovided with the glucose values. The algorithm may use the time stampassociated with a BGV to determine which set of data (e.g., which 10points) need to be averaged to yield an integrated sensor signal that ismatched or paired with the glucose value. In preferred embodiments, thesensor system 8 and paired device 14 in communication with each otherare synchronized, thereby ensuring proper interpretation of time stamps.

In some embodiments, when there is a delay in communication between thepaired device 14 and sensor system 8, the buffer can be configured tostore more integrated sensor signals. For example, if there is a 5minute delay in communication, the buffer may be configured to store thepresent integrated sensor signal and a past integrated sensor signal ora total of 20 30 second values.

Also, while the integration window may remain a fixed duration (e.g., 5minutes), the data presentation on paired device 14 does not need to belimited to one point for the fixed duration. For example, if it isdesired to have the glucose values displayed within 2.5 minuteintervals, every 2.5 minutes the last ten 30 second values may beaveraged and fed into an integration algorithm, thereby providing amoving average.

Other tools or strategies for improving the time lag and accuracy of thesensor system 8 include using adaptive sampling. For example, as theglucose rate of change increases, the sampling rate can also increase(e.g., shorter sample times or shorter integration window, greaternumber of samples, etc.).

Embodiments of the present disclosure are described above and below withreference to flowchart illustrations of methods, apparatus, and computerprogram products. It will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by execution of computer programinstructions. These computer program instructions may be loaded onto acomputer or other programmable data processing apparatus (such as acontroller, microcontroller, microprocessor or the like) in a sensorelectronics system to produce a machine, such that the instructionswhich execute on the computer or other programmable data processingapparatus create instructions for implementing the functions specifiedin the flowchart block or blocks. These computer program instructionsmay also be stored in a computer-readable memory that can direct acomputer or other programmable data processing apparatus to function ina particular manner, such that the instructions stored in thecomputer-readable memory produce an article of manufacture includinginstructions which implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions which execute on the computer or otherprogrammable apparatus provide steps for implementing the functionsspecified in the flowchart block or blocks presented herein.

Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. Pat. Nos.4,757,022; 4,994,167; 6,001,067; 6,558,321; 6,702,857; 6,741,877;6,862,465; 6,931,327; 7,074,307; 7,081,195; 7,108,778; 7,110,803;7,134,999; 7,136,689; 7,192,450; 7,226,978; 7,276,029; 7,310,544;7,364,592; 7,366,556; 7,379,765; 7,424,318; 7,460,898; 7,467,003;7,471,972; 7,494,465; 7,497,827; 7,519,408; 7,583,990; 7,591,801;7,599,726; 7,613,491; 7,615,007; 7,632,228; 7,637,868; 7,640,048;7,651,596; 7,654,956; 7,657,297; 7,711,402; 7,713,574; 7,715,893;7,761,130; 7,771,352; 7,774,145; 7,775,975; 7,778,680; 7,783,333;7,792,562; 7,797,028; 7,826,981; 7,828,728; 7,831,287; 7,835,777;7,857,760; 7,860,545; 7,875,293; 7,881,763; 7,885,697; 7,896,809;7,899,511; 7,901,354; 7,905,833; 7,914,450; 7,917,186; 7,920,906;7,925,321; 7,927,274; 7,933,639; 7,935,057; 7,946,984; 7,949,381;7,955,261; 7,959,569; 7,970,448; 7,974,672; 7,976,492; 7,979,104;7,986,986; 7,998,071; 8,000,901; 8,005,524; 8,005,525; 8,010,174;8,027,708; 8,050,731; 8,052,601; 8,053,018; 8,060,173; 8,060,174;8,064,977; 8,073,519; 8,073,520; 8,118,877; 8,128,562; 8,133,178;8,150,488; 8,155,723; 8,160,669; 8,160,671; 8,167,801; 8,170,803;8,195,265; 8,206,297; 8,216,139; 8,229,534; 8,229,535; 8,229,536;8,231,531; 8,233,958; 8,233,959; 8,249,684; 8,251,906; 8,255,030;8,255,032; 8,255,033; 8,257,259; 8,260,393; 8,265,725; 8,275,437;8,275,438; 8,277,713; 8,280,475; 8,282,549; 8,282,550; 8,285,354;8,287,453; 8,290,559; 8,290,560; 8,290,561; 8,290,562; 8,292,810;8,298,142; 8,311,749; 8,313,434; 8,321,149; 8,332,008; 8,346,338;8,364,229; 8,369,919; 8,374,667; 8,386,004; and 8,394,021.

Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. PatentPublication No. 2003-0032874-A1; U.S. Patent Publication No.2005-0033132-A1; U.S. Patent Publication No. 2005-0051427-A1; U.S.Patent Publication No. 2005-0090607-A1; U.S. Patent Publication No.2005-0176136-A1; U.S. Patent Publication No. 2005-0245799-A1; U.S.Patent Publication No. 2006-0015020-A1; U.S. Patent Publication No.2006-0016700-A1; U.S. Patent Publication No. 2006-0020188-A1; U.S.Patent Publication No. 2006-0020190-A1; U.S. Patent Publication No.2006-0020191-A1; U.S. Patent Publication No. 2006-0020192-A1; U.S.Patent Publication No. 2006-0036140-A1; U.S. Patent Publication No.2006-0036143-A1; U.S. Patent Publication No. 2006-0040402-A1; U.S.Patent Publication No. 2006-0068208-A1; U.S. Patent Publication No.2006-0142651-A1; U.S. Patent Publication No. 2006-0155180-A1; U.S.Patent Publication No. 2006-0198864-A1; U.S. Patent Publication No.2006-0200020-A1; U.S. Patent Publication No. 2006-0200022-A1; U.S.Patent Publication No. 2006-0200970-A1; U.S. Patent Publication No.2006-0204536-A1; U.S. Patent Publication No. 2006-0224108-A1; U.S.Patent Publication No. 2006-0235285-A1; U.S. Patent Publication No.2006-0249381-A1; U.S. Patent Publication No. 2006-0252027-A1; U.S.Patent Publication No. 2006-0253012-A1; U.S. Patent Publication No.2006-0257995-A1; U.S. Patent Publication No. 2006-0258761-A1; U.S.Patent Publication No. 2006-0263763-A1; U.S. Patent Publication No.2006-0270922-A1; U.S. Patent Publication No. 2006-0270923-A1; U.S.Patent Publication No. 2007-0027370-A1; U.S. Patent Publication No.2007-0032706-A1; U.S. Patent Publication No. 2007-0032718-A1; U.S.Patent Publication No. 2007-0045902-A1; U.S. Patent Publication No.2007-0059196-A1; U.S. Patent Publication No. 2007-0066873-A1; U.S.Patent Publication No. 2007-0173709-A1; U.S. Patent Publication No.2007-0173710-A1; U.S. Patent Publication No. 2007-0208245-A1; U.S.Patent Publication No. 2007-0208246-A1; U.S. Patent Publication No.2007-0232879-A1; U.S. Patent Publication No. 2008-0045824-A1; U.S.Patent Publication No. 2008-0083617-A1; U.S. Patent Publication No.2008-0086044-A1; U.S. Patent Publication No. 2008-0108942-A1; U.S.Patent Publication No. 2008-0119703-A1; U.S. Patent Publication No.2008-0119704-A1; U.S. Patent Publication No. 2008-0119706-A1; U.S.Patent Publication No. 2008-0183061-A1; U.S. Patent Publication No.2008-0183399-A1; U.S. Patent Publication No. 2008-0188731-A1; U.S.Patent Publication No. 2008-0189051-A1; U.S. Patent Publication No.2008-0194938-A1; U.S. Patent Publication No. 2008-0197024-A1; U.S.Patent Publication No. 2008-0200788-A1; U.S. Patent Publication No.2008-0200789-A1; U.S. Patent Publication No. 2008-0200791-A1; U.S.Patent Publication No. 2008-0214915-A1; U.S. Patent Publication No.2008-0228054-A1; U.S. Patent Publication No. 2008-0242961-A1; U.S.Patent Publication No. 2008-0262469-A1; U.S. Patent Publication No.2008-0275313-A1; U.S. Patent Publication No. 2008-0287765-A1; U.S.Patent Publication No. 2008-0306368-A1; U.S. Patent Publication No.2008-0306434-A1; U.S. Patent Publication No. 2008-0306435-A1; U.S.Patent Publication No. 2008-0306444-A1; U.S. Patent Publication No.2009-0018424-A1; U.S. Patent Publication No. 2009-0030294-A1; U.S.Patent Publication No. 2009-0036758-A1; U.S. Patent Publication No.2009-0036763-A1; U.S. Patent Publication No. 2009-0043181-A1; U.S.Patent Publication No. 2009-0043182-A1; U.S. Patent Publication No.2009-0043525-A1; U.S. Patent Publication No. 2009-0045055-A1; U.S.Patent Publication No. 2009-0062633-A1; U.S. Patent Publication No.2009-0062635-A1; U.S. Patent Publication No. 2009-0076360-A1; U.S.Patent Publication No. 2009-0099436-A1; U.S. Patent Publication No.2009-0124877-A1; U.S. Patent Publication No. 2009-0124879-A1; U.S.Patent Publication No. 2009-0124964-A1; U.S. Patent Publication No.2009-0131769-A1; U.S. Patent Publication No. 2009-0131777-A1; U.S.Patent Publication No. 2009-0137886-A1; U.S. Patent Publication No.2009-0137887-A1; U.S. Patent Publication No. 2009-0143659-A1; U.S.Patent Publication No. 2009-0143660-A1; U.S. Patent Publication No.2009-0156919-A1; U.S. Patent Publication No. 2009-0163790-A1; U.S.Patent Publication No. 2009-0178459-A1; U.S. Patent Publication No.2009-0192366-A1; U.S. Patent Publication No. 2009-0192380-A1; U.S.Patent Publication No. 2009-0192722-A1; U.S. Patent Publication No.2009-0192724-A1; U.S. Patent Publication No. 2009-0192751-A1; U.S.Patent Publication No. 2009-0203981-A1; U.S. Patent Publication No.2009-0216103-A1; U.S. Patent Publication No. 2009-0240120-A1; U.S.Patent Publication No. 2009-0240193-A1; U.S. Patent Publication No.2009-0242399-A1; U.S. Patent Publication No. 2009-0242425-A1; U.S.Patent Publication No. 2009-0247855-A1; U.S. Patent Publication No.2009-0247856-A1; U.S. Patent Publication No. 2009-0287074-A1; U.S.Patent Publication No. 2009-0299155-A1; U.S. Patent Publication No.2009-0299156-A1; U.S. Patent Publication No. 2009-0299162-A1; U.S.Patent Publication No. 2010-0010331-A1; U.S. Patent Publication No.2010-0010332-A1; U.S. Patent Publication No. 2010-0016687-A1; U.S.Patent Publication No. 2010-0016698-A1; U.S. Patent Publication No.2010-0030484-A1; U.S. Patent Publication No. 2010-0036215-A1; U.S.Patent Publication No. 2010-0036225-A1; U.S. Patent Publication No.2010-0041971-A1; U.S. Patent Publication No. 2010-0045465-A1; U.S.Patent Publication No. 2010-0049024-A1; U.S. Patent Publication No.2010-0076283-A1; U.S. Patent Publication No. 2010-0081908-A1; U.S.Patent Publication No. 2010-0081910-A1; U.S. Patent Publication No.2010-0087724-A1; U.S. Patent Publication No. 2010-0096259-A1; U.S.Patent Publication No. 2010-0121169-A1; U.S. Patent Publication No.2010-0161269-A1; U.S. Patent Publication No. 2010-0168540-A1; U.S.Patent Publication No. 2010-0168541-A1; U.S. Patent Publication No.2010-0168542-A1; U.S. Patent Publication No. 2010-0168543-A1; U.S.Patent Publication No. 2010-0168544-A1; U.S. Patent Publication No.2010-0168545-A1; U.S. Patent Publication No. 2010-0168546-A1; U.S.Patent Publication No. 2010-0168657-A1; U.S. Patent Publication No.2010-0174157-A1; U.S. Patent Publication No. 2010-0174158-A1; U.S.Patent Publication No. 2010-0174163-A1; U.S. Patent Publication No.2010-0174164-A1; U.S. Patent Publication No. 2010-0174165-A1; U.S.Patent Publication No. 2010-0174166-A1; U.S. Patent Publication No.2010-0174167-A1; U.S. Patent Publication No. 2010-0179401-A1; U.S.Patent Publication No. 2010-0179402-A1; U.S. Patent Publication No.2010-0179404-A1; U.S. Patent Publication No. 2010-0179408-A1; U.S.Patent Publication No. 2010-0179409-A1; U.S. Patent Publication No.2010-0185065-A1; U.S. Patent Publication No. 2010-0185069-A1; U.S.Patent Publication No. 2010-0185070-A1; U.S. Patent Publication No.2010-0185071-A1; U.S. Patent Publication No. 2010-0185075-A1; U.S.Patent Publication No. 2010-0191082-A1; U.S. Patent Publication No.2010-0198035-A1; U.S. Patent Publication No. 2010-0198036-A1; U.S.Patent Publication No. 2010-0212583-A1; U.S. Patent Publication No.2010-0217557-A1; U.S. Patent Publication No. 2010-0223013-A1; U.S.Patent Publication No. 2010-0223022-A1; U.S. Patent Publication No.2010-0223023-A1; U.S. Patent Publication No. 2010-0228109-A1; U.S.Patent Publication No. 2010-0228497-A1; U.S. Patent Publication No.2010-0240975-A1; U.S. Patent Publication No. 2010-0240976C1; U.S. PatentPublication No. 2010-0261987-A1; U.S. Patent Publication No.2010-0274107-A1; U.S. Patent Publication No. 2010-0280341-A1; U.S.Patent Publication No. 2010-0286496-A1; U.S. Patent Publication No.2010-0298684-A1; U.S. Patent Publication No. 2010-0324403-A1; U.S.Patent Publication No. 2010-0331656-A1; U.S. Patent Publication No.2010-0331657-A1; U.S. Patent Publication No. 2011-0004085-A1; U.S.Patent Publication No. 2011-0009727-A1; U.S. Patent Publication No.2011-0024043-A1; U.S. Patent Publication No. 2011-0024307-A1; U.S.Patent Publication No. 2011-0027127-A1; U.S. Patent Publication No.2011-0027453-A1; U.S. Patent Publication No. 2011-0027458-A1; U.S.Patent Publication No. 2011-0028815-A1; U.S. Patent Publication No.2011-0028816-A1; U.S. Patent Publication No. 2011-0046467-A1; U.S.Patent Publication No. 2011-0077490-A1; U.S. Patent Publication No.2011-0118579-A1; U.S. Patent Publication No. 2011-0124992-A1; U.S.Patent Publication No. 2011-0125410-A1; U.S. Patent Publication No.2011-0130970-A1; U.S. Patent Publication No. 2011-0130971-A1; U.S.Patent Publication No. 2011-0130998-A1; U.S. Patent Publication No.2011-0144465-A1; U.S. Patent Publication No. 2011-0178378-A1; U.S.Patent Publication No. 2011-0190614-A1; U.S. Patent Publication No.2011-0201910-A1; U.S. Patent Publication No. 2011-0201911-A1; U.S.Patent Publication No. 2011-0218414-A1; U.S. Patent Publication No.2011-0231140-A1; U.S. Patent Publication No. 2011-0231141-A1; U.S.Patent Publication No. 2011-0231142-A1; U.S. Patent Publication No.2011-0253533-A1; U.S. Patent Publication No. 2011-0263958-A1; U.S.Patent Publication No. 2011-0270062-A1; U.S. Patent Publication No.2011-0270158-A1; U.S. Patent Publication No. 2011-0275919-A1; U.S.Patent Publication No. 2011-0290645-A1; U.S. Patent Publication No.2011-0313543-A1; U.S. Patent Publication No. 2011-0320130-A1; U.S.Patent Publication No. 2012-0035445-A1; U.S. Patent Publication No.2012-0040101-A1; U.S. Patent Publication No. 2012-0046534-A1; U.S.Patent Publication No. 2012-0078071-A1; U.S. Patent Publication No.2012-0108934-A1; U.S. Patent Publication No. 2012-0130214-A1; U.S.Patent Publication No. 2012-0172691-A1; U.S. Patent Publication No.2012-0179014-A1; U.S. Patent Publication No. 2012-0186581-A1; U.S.Patent Publication No. 2012-0190953-A1; U.S. Patent Publication No.2012-0191063-A1; U.S. Patent Publication No. 2012-0203467-A1; U.S.Patent Publication No. 2012-0209098-A1; U.S. Patent Publication No.2012-0215086-A1; U.S. Patent Publication No. 2012-0215087-A1; U.S.Patent Publication No. 2012-0215201-A1; U.S. Patent Publication No.2012-0215461-A1; U.S. Patent Publication No. 2012-0215462-A1; U.S.Patent Publication No. 2012-0215496-A1; U.S. Patent Publication No.2012-0220979-A1; U.S. Patent Publication No. 2012-0226121-A1; U.S.Patent Publication No. 2012-0228134-A1; U.S. Patent Publication No.2012-0238852-A1; U.S. Patent Publication No. 2012-0245448-A1; U.S.Patent Publication No. 2012-0245855-A1; U.S. Patent Publication No.2012-0255875-A1; U.S. Patent Publication No. 2012-0258748-A1; U.S.Patent Publication No. 2012-0259191-A1; U.S. Patent Publication No.2012-0260323-A1; U.S. Patent Publication No. 2012-0262298-A1; U.S.Patent Publication No. 2012-0265035-A1; U.S. Patent Publication No.2012-0265036-A1; U.S. Patent Publication No. 2012-0265037-A1; U.S.Patent Publication No. 2012-0277562-A1; U.S. Patent Publication No.2012-0277566-A1; U.S. Patent Publication No. 2012-0283541-A1; U.S.Patent Publication No. 2012-0283543-A1; U.S. Patent Publication No.2012-0296311-A1; U.S. Patent Publication No. 2012-0302854-A1; U.S.Patent Publication No. 2012-0302855-A1; U.S. Patent Publication No.2012-0323100-A1; U.S. Patent Publication No. 2013-0012798-A1; U.S.Patent Publication No. 2013-0030273-A1; U.S. Patent Publication No.2013-0035575-A1; U.S. Patent Publication No. 2013-0035865-A1; U.S.Patent Publication No. 2013-0035871-A1; U.S. Patent Publication No.2005-0056552-A1; U.S. Patent Publication No. 2005-0182451-A1; U.S.Patent Publication No. 2013000536650A1; and U.S. Patent Publication No.2013-0053666-A1.

Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. applicationSer. No. 09/447,227 filed on Nov. 22, 1999 and entitled “DEVICE ANDMETHOD FOR DETERMINING ANALYTE LEVELS”; U.S. application Ser. No.12/828,967 filed on Jul. 1, 2010 and entitled “HOUSING FOR ANINTRAVASCULAR SENSOR”; U.S. application Ser. No. 13/461,625 filed on May1, 2012 and entitled “DUAL ELECTRODE SYSTEM FOR A CONTINUOUS ANALYTESENSOR”; U.S. application Ser. No. 13/594,602 filed on Aug. 24, 2012 andentitled “POLYMER MEMBRANES FOR CONTINUOUS ANALYTE SENSORS”; U.S.application Ser. No. 13/594,734 filed on Aug. 24, 2012 and entitled“POLYMER MEMBRANES FOR CONTINUOUS ANALYTE SENSORS”; U.S. applicationSer. No. 13/607,162 filed on Sep. 7, 2012 and entitled “SYSTEM ANDMETHODS FOR PROCESSING ANALYTE SENSOR DATA FOR SENSOR CALIBRATION”; U.S.application Ser. No. 13/624,727 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/624,808 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/624,812 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/732,848 filed on Jan. 2, 2013 and entitled“ANALYTE SENSORS HAVING A SIGNAL-TO-NOISE RATIO SUBSTANTIALLY UNAFFECTEDBY NON-CONSTANT NOISE”; U.S. application Ser. No. 13/733,742 filed onJan. 3, 2013 and entitled “END OF LIFE DETECTION FOR ANALYTE SENSORS”;U.S. application Ser. No. 13/733,810 filed on Jan. 3, 2013 and entitled“OUTLIER DETECTION FOR ANALYTE SENSORS”; U.S. application Ser. No.13/742,178 filed on Jan. 15, 2013 and entitled “SYSTEMS AND METHODS FORPROCESSING SENSOR DATA”; U.S. application Ser. No. 13/742,694 filed onJan. 16, 2013 and entitled “SYSTEMS AND METHODS FOR PROVIDING SENSITIVEAND SPECIFIC ALARMS”; U.S. application Ser. No. 13/742,841 filed on Jan.16, 2013 and entitled “SYSTEMS AND METHODS FOR DYNAMICALLY ANDINTELLIGENTLY MONITORING A HOST'S GLYCEMIC CONDITION AFTER AN ALERT ISTRIGGERED”; U.S. application Ser. No. 13/747,746 filed on Jan. 23, 2013and entitled “DEVICES, SYSTEMS, AND METHODS TO COMPENSATE FOR EFFECTS OFTEMPERATURE ON IMPLANTABLE SENSORS”; U.S. application Ser. No.13/779,607 filed on Feb. 27, 2013 and entitled “ZWITTERION SURFACEMODIFICATIONS FOR CONTINUOUS SENSORS”; U.S. application Ser. No.13/780,808 filed on Feb. 28, 2013 and entitled “SENSORS FOR CONTINUOUSANALYTE MONITORING, AND RELATED METHODS”; U.S. application Ser. No.13/784,523 filed on Mar. 4, 2013 and entitled “ANALYTE SENSOR WITHINCREASED REFERENCE CAPACITY”; U.S. application Ser. No. 13/789,371filed on Mar. 7, 2013 and entitled “MULTIPLE ELECTRODE SYSTEM FOR ACONTINUOUS ANALYTE SENSOR, AND RELATED METHODS”; U.S. application Ser.No. 13/789,279 filed on Mar. 7, 2013 and entitled “USE OF SENSORREDUNDANCY TO DETECT SENSOR FAILURES”; U.S. application Ser. No.13/789,339 filed on Mar. 7, 2013 and entitled “DYNAMIC REPORT BUILDING”;U.S. application Ser. No. 13/789,341 filed on Mar. 7, 2013 and entitled“REPORTING MODULES”; U.S. application Ser. No. 13/790,281 filed on Mar.8, 2013 and entitled “SYSTEMS AND METHODS FOR MANAGING GLYCEMICVARIABILITY”; U.S. application Ser. No. 13/796,185 filed on Mar. 12,2013 and entitled “SYSTEMS AND METHODS FOR PROCESSING ANALYTE SENSORDATA”; U.S. application Ser. No. 13/796,642 filed on Mar. 12, 2013 andentitled “SYSTEMS AND METHODS FOR PROCESSING ANALYTE SENSOR DATA”; U.S.application Ser. No. 13/801,445 filed on Mar. 13, 2013 and entitled“SYSTEMS AND METHODS FOR LEVERAGING SMARTPHONE FEATURES IN CONTINUOUSGLUCOSE MONITORING”; U.S. application Ser. No. 13/802,424 filed on Mar.13, 2013 and entitled “SYSTEMS AND METHODS FOR LEVERAGING SMARTPHONEFEATURES IN CONTINUOUS GLUCOSE MONITORING”; U.S. application Ser. No.13/802,237 filed on Mar. 13, 2013 and entitled “SYSTEMS AND METHODS FORLEVERAGING SMARTPHONE FEATURES IN CONTINUOUS GLUCOSE MONITORING”; andU.S. application Ser. No. 13/802,317 filed on Mar. 13, 2013 and entitled“SYSTEMS AND METHODS FOR LEVERAGING SMARTPHONE FEATURES IN CONTINUOUSGLUCOSE MONITORING”.

The above description presents the best mode contemplated for carryingout the present invention, and of the manner and process of making andusing it, in such full, clear, concise, and exact terms as to enable anyperson skilled in the art to which it pertains to make and use thisinvention. This invention is, however, susceptible to modifications andalternate constructions from that discussed above that are fullyequivalent. Consequently, this invention is not limited to theparticular embodiments disclosed. On the contrary, this invention coversall modifications and alternate constructions coming within the spiritand scope of the invention as generally expressed by the followingclaims, which particularly point out and distinctly claim the subjectmatter of the invention. While the disclosure has been illustrated anddescribed in detail in the drawings and foregoing description, suchillustration and description are to be considered illustrative orexemplary and not restrictive.

All references cited herein are incorporated herein by reference intheir entirety. To the extent publications and patents or patentapplications incorporated by reference contradict the disclosurecontained in the specification, the specification is intended tosupersede and/or take precedence over any such contradictory material.

Unless otherwise defined, all terms (including technical and scientificterms) are to be given their ordinary and customary meaning to a personof ordinary skill in the art, and are not to be limited to a special orcustomized meaning unless expressly so defined herein. It should benoted that the use of particular terminology when describing certainfeatures or aspects of the disclosure should not be taken to imply thatthe terminology is being re-defined herein to be restricted to includeany specific characteristics of the features or aspects of thedisclosure with which that terminology is associated. Terms and phrasesused in this application, and variations thereof, especially in theappended claims, unless otherwise expressly stated, should be construedas open ended as opposed to limiting. As examples of the foregoing, theterm ‘including’ should be read to mean ‘including, without limitation,’including but not limited to,' or the like; the term ‘comprising’ asused herein is synonymous with ‘including,’ ‘containing,’ or‘characterized by,’ and is inclusive or open-ended and does not excludeadditional, unrecited elements or method steps; the term ‘having’ shouldbe interpreted as ‘having at least;’ the term ‘includes’ should beinterpreted as ‘includes but is not limited to;’ the term ‘example’ isused to provide exemplary instances of the item in discussion, not anexhaustive or limiting list thereof; adjectives such as ‘known’,‘normal’, ‘standard’, and terms of similar meaning should not beconstrued as limiting the item described to a given time period or to anitem available as of a given time, but instead should be read toencompass known, normal, or standard technologies that may be availableor known now or at any time in the future; and use of terms like‘preferably,’ preferred,“desired,” or ‘desirable,’ and words of similarmeaning should not be understood as implying that certain features arecritical, essential, or even important to the structure or function ofthe invention, but instead as merely intended to highlight alternativeor additional features that may or may not be utilized in a particularembodiment of the invention. Likewise, a group of items linked with theconjunction ‘and’ should not be read as requiring that each and everyone of those items be present in the grouping, but rather should be readas ‘and/or’ unless expressly stated otherwise. Similarly, a group ofitems linked with the conjunction ‘or’ should not be read as requiringmutual exclusivity among that group, but rather should be read as‘and/or’ unless expressly stated otherwise.

Where a range of values is provided, it is understood that the upper andlower limit, and each intervening value between the upper and lowerlimit of the range is encompassed within the embodiments.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity. The indefinite article ‘a’ or ‘an’ does not exclude aplurality. A single processor or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Anyreference signs in the claims should not be construed as limiting thescope.

It will be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases ‘at least one’ and ‘one or more’ to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles ‘a’ or ‘an’ limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases‘one or more’ or ‘at least one’ and indefinite articles such as ‘a’ or‘an’ (e.g., ‘a’ and/or ‘an’ should typically be interpreted to mean ‘atleast one’ or ‘one or more’); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of ‘two recitations,’ without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to ‘at least one of A, B, and C, etc.’ is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., ‘a system having at least one ofA, B, and C’ would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to ‘at least one of A, B, or C, etc.’ is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., ‘a system having at leastone of A, B, or C’ would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase ‘A or B’ will be understood toinclude the possibilities of ‘A’ or ‘B’ or ‘A and B.’

All numbers expressing quantities of ingredients, reaction conditions,and so forth used in the specification are to be understood as beingmodified in all instances by the term ‘about.’ Accordingly, unlessindicated to the contrary, the numerical parameters set forth herein areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of anyclaims in any application claiming priority to the present application,each numerical parameter should be construed in light of the number ofsignificant digits and ordinary rounding approaches.

Furthermore, although the foregoing has been described in some detail byway of illustrations and examples for purposes of clarity andunderstanding, it is apparent to those skilled in the art that certainchanges and modifications may be practiced. Therefore, the descriptionand examples should not be construed as limiting the scope of theinvention to the specific embodiments and examples described herein, butrather to also cover all modification and alternatives coming with thetrue scope and spirit of the invention.

What is claimed is:
 1. A transcutaneous glucose sensor system, thesystem comprising: a transcutaneous glucose sensor comprising an in vivoportion, wherein the transcutaneous sensor is an electrochemical sensor,wherein the transcutaneous glucose sensor comprises a membrane and atleast one electrode, wherein the at least one electrode is a workingelectrode; a sensor electronics unit operatively connected to thetranscutaneous glucose sensor, wherein the sensor electronics unitcomprises circuitry associated with measuring and processing sensor datareceived from the transcutaneous glucose sensor; and a display deviceoperatively connected to the sensor electronics unit, wherein thedisplay device is configured to display a glucose value.